Democratic U.S. Sens. Jon Tester of Montana, left, and Sherrod Brown of Ohio, right, are seen as the chamber’s most vulnerable incumbent Democrats in 2024. In this photo, Brown, the Senate Banking, Housing and Urban Affairs Committee chairman, talks with committee member Tester during a hearing about the Consumer Financial Protection Bureau on Capitol Hill on Dec. 15, 2022 in Washington, D.C. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON — Political consultants and Beltway pollsters are setting up camp in purple states to join a towering battle for control of a narrowly split U.S. Senate, but come November, only the voters will make that choice.

The road to the majority in the upper chamber of Congress mostly runs through Arizona, Montana and Ohio, where candidates have already spent months pitching their accomplishments and plans. And while it’s still early, the presence of former President Donald Trump at the top of the ballot and Democrats’ stress on abortion rights both look likely to remain consequential through the summer and fall, political experts predict.

The struggle for control is also fluid and will likely remain that way until all the ballots are counted. The influential Cook Political Report with Amy Walter changed its rating for Nevada’s Senate contest on Wednesday, moving the state from “lean Democratic” to the toss-up category and increasing pressure on incumbent Democratic Sen. Jacky Rosen, who will face the Republican nominee following a June primary.

J. Miles Coleman, associate editor of Sabato’s Crystal Ball at the University of Virginia Center for Politics, said in an interview with States Newsroom that Democrats are playing defense in multiple states, though they will be on offense in Florida and Texas despite long odds.

“I haven’t been designating the Republicans as favorites to flip the chamber, but they do have an easier path to getting to a majority than the Democrats do,” Coleman said.

Republicans only need to pick up West Virginia to hold 50 seats in the Senate, which would put them in the majority should Trump win election. Longtime Democratic moderate Sen. Joe Manchin III is retiring in red-leaning West Virginia.

GOP candidates winning any one of the three toss-up races in Arizona, Montana and Ohio would push Republicans up to at least a 51-seat majority as long as they hold onto all their other seats, Coleman said.

“With all that in mind, I would say this year the biggest goal of Democrats is going to be to limit their losses,” he said.

Jessica Taylor, U.S. Senate and governors editor at The Cook Political Report, said during an interview with States Newsroom that this year holds a “very unfavorable Senate map for Democrats.”

“The bottom line is that there is no room for error,” Taylor said. “So even if they win the presidency, they cannot lose any incumbents.”

During the 2020 campaign, Trump’s unpopularity dragged down some of the GOP Senate candidates, leading Republicans to lose control of the chamber, but the reverse could be true this year, Taylor said.

“Democrats have to grapple with the fact that Biden is even more unpopular than Trump was at this point,” she said. “And the question becomes, how much can Democratic incumbents outrun him, especially when you have them in states that (Trump) won twice.”

Trump won in Ohio and Montana in both 2016 and 2020, though he lost in Arizona in 2020 after winning the state four years prior. That could be bad news for Democrats in those Senate races.

“In 2016, every single Senate race went the same way as the presidential race did,” Taylor said. “And in 2020, the only state that deviated was Maine, which Susan Collins was able to win even as (President Joe) Biden did win the state.”

The Senate incumbents seeking reelection this year last faced voters in 2018, a midterm election year. Senate terms run for six years.

Open seat in Arizona

Arizona’s Senate race doesn’t include an incumbent after Kyrsten Sinema announced her retirement, leaving the field open ahead of the July 30 primary.

Democratic Rep. Ruben Gallego and Republican Kari Lake are expected to advance to the general election, though there are numerous Republicans challenging Lake in the primary.

The winner of the general election race, Coleman said, will likely gain the support of the “John McCain-type Republicans, who aren’t too happy about having to vote for a Democrat, but they really don’t like how extreme Lake is.”

“It’s one of the things that was working against the Republicans in 2022, because they really should have retaken the Senate,” Coleman said. “But in some of those races, the candidates that Mitch McConnell would have liked, were not the same candidates that Trump liked.”

McConnell, the Republican leader in the Senate, and Trump have long had differences.

Gallego, a former U.S. Marine, has represented the state’s 3rd Congressional District in the U.S. House since 2015 after spending four years in the state legislature.

Lake mounted an unsuccessful campaign for governor in 2022, later claiming she lost due to fraud, but has opted not to defend herself in the defamation lawsuit filed by Republican Maricopa County Recorder Stephen Richer.

Lake posted on social media that she believed that by “participating in this lawsuit, it would only serve to legitimize this perversion of our legal system and allow bad actors to interfere in our upcoming election.”

Arizona Democratic Party Chairwoman Yolanda Bejarano said in an interview with States Newsroom that top issues voters are focused on this year are abortion access, immigration, water and democracy.

Voters, she said, aren’t likely to forget that Republicans in the Senate, urged on by Trump, blocked a bipartisan immigration and border security bill from moving forward. Sinema brokered that deal alongside Connecticut Democratic Sen. Chris Murphy and Oklahoma GOP Sen. James Lankford.

“Democrats put up, actually, a bipartisan plan, a border solution, and it was rejected, because Trump told his members of Congress that this would not help them in his election,” Bejarano said.

The Arizona Senate race is also likely to be influenced by a ballot question that could add abortion access to the state Constitution. The group leading the effort, Arizona for Abortion Access, said Tuesday it has collected more than 500,000 signatures, well above the required 383,923 ahead of a July deadline.

“Arizona currently bans most abortions after 15 weeks of pregnancy. And what this would do, is it would guarantee the right to an abortion up until fetal viability,” Bejarano said, referring to a benchmark that is typically about 22 to 24 weeks into a pregnancy.

“So yeah, I think this is a winning issue for us because Arizonans do not want the government interfering in those personal decisions,” she added.

The Arizona Republican Party did not return requests for an interview.

Tester defends Montana seat

In Montana, Democratic Sen. Jon Tester, chair of the Veterans Affairs Committee and the Defense Appropriations Subcommittee, will likely face former Navy SEAL Tim Sheehy, though Republican voters will make that decision during their June 4 primary.

Tester has represented the state in the U.S. Senate since he was first elected in 2006, defeating his Republican opponent by a margin of just over 3,500 votes. Montana voters reelected him in 2012 by providing him 18,000 more votes than his GOP opponent and in 2018 by about the same margin.

Sheehy is one of several Republican Senate candidates with significant wealth running this election cycle, a feature that could help or hamstring him with voters, Taylor said.

“What Republicans have turned to this time is they have a lot of wealthy candidates that are running and they’re able to self-finance their races,” Taylor said. “So that does give them an advantage.”

Eric Hovde, who is expected to clinch the Republican nomination in Wisconsin, and David McCormick, who is likely to win Pennsylvania’s GOP primary later this month given that he’s the only name on the ballot, are among the wealthier Republicans running this cycle, she said.

In Wisconsin, Republicans hope to defeat Democratic Sen. Tammy Baldwin, who won in 2018 with 55.4% of the vote. In Pennsylvania, they are targeting Democratic Sen. Bob Casey, who won six years ago with 55.7%.

Both states are rated as lean Democratic by The Cook Political Report.

The wealth of the Republicans could become a “double-edged sword” for those candidates, Taylor said.

“That’s just where I think we have to wait and see which wins out — partisanship or the candidate quality,” Taylor said. “And we saw, certainly in 2022, the candidate quality mattered, but that was during a midterm year, not during a presidential year.”

Montana reproductive rights organizations are also moving forward with putting a question directly before voters that could enshrine abortion access in the state’s Constitution, an issue that may drive more voters to the polls in November.

Democrats believe abortion rights are a winning issue for them in the wake of the Supreme Court’s decision to overturn Roe v. Wade.

That theory has been supported by voters approving ballot questions in favor of abortion rights in several states during the last two years, including Kansas, Kentucky, Michigan and Ohio.

Brawl in the Buckeye State

In Ohio, Democratic Sen. Sherrod Brown, chair of the Committee on Banking, Housing, and Urban Affairs, and Bernie Moreno, who won the Republican primary in mid-March, will compete for voters’ support during the general election this November.

Brown won his first race for U.S. Senate in 2006 with 56% of the vote. Buckeye State residents reelected him in 2012 with 50.7% of the vote and again in 2018 with 53.4% of the vote.

Ohio is the “most vulnerable” state on the map for Democrats, according to Taylor’s analysis, though she said Moreno is still a somewhat unknown candidate who will need to prove himself to voters.

All three of the GOP candidates in the toss-up states of Arizona, Montana and Ohio have endorsements from Trump, a feature they’re likely to tout on the campaign trail, but that Democrats could use to paint them as too partisan for swing voters.

Nevada moves to toss-up

Nevada joined the other three states on Wednesday as a toss-up race, according to the Cook Political Report, though Sabato’s Crystal Ball continues to categorize the state as “leans Democratic.”

The change in ratings from CPR puts more pressure on Democrats and Rosen to hold the line, while offering Republicans the possibility to have an even larger Senate majority.

Taylor wrote in the ratings change that “ultimately we are moving this race because of the unique forces at play in Nevada.”

“A combination of a newer electorate that Rosen must win over, Biden’s lagging numbers, and the unique post-COVID economic hangover in Nevada make this race a Toss Up,” she wrote

The Cook Political Report would “would certainly reassess our rating,” if? Army veteran Sam Brown doesn’t win the GOP primary to challenge Rosen in the general election.

At the moment, Taylor wrote, the “problems Democrats have in Arizona, especially on the issue of immigration and with lagging Latino voters, are similar in Nevada, though even Republicans are skeptical of polls that show them winning a majority of Hispanic voters.”

“Nonetheless, Republicans caution that the turnout machine the late Sen. Harry Reid built in the Silver State is still alive and well and will be active for Biden and especially Rosen, who was the former Senate majority leader’s protege,” Taylor added.

Democrats won the state in both the 2016 and 2020 presidential contests, but not by much. Hillary Clinton won by more than 27,000 votes in 2016 and Biden won in 2020 by more than 33,500 votes.

Rosen won her first term in the Senate in 2018 by a margin of nearly 49,000 more votes than her Republican opponent.

This year’s primary election on June 11 will determine exactly which Republican will challenge Rosen in the general election.

A fluid Senate outlook

Other states could come into play the closer voters come to Election Day, including bright-blue Maryland moving towards Republicans with the surprise entry of an ex-governor, as Florida and Texas possibly inch a bit closer to Democratic control.

The more expensive media market in Texas and Florida could hamper Democratic efforts to pick up either of those seats, currently held by Ted Cruz and Rick Scott, according to Coleman.

“Eventually you could have the (Democratic Senatorial Campaign Committee) or the Senate Majority PAC having to calculate, ‘Okay, well, do we spend more to shore up Tester and Brown, or do we want to go chase Texas?” Coleman said.

Scott, former governor of Florida, won his first term to the U.S. Senate in 2018 by defeating former Democratic Sen. Bill Nelson, who has since become the NASA administrator for the Biden administration. The two were separated by just 10,033 votes out of more than 8.1 million ballots cast.

This November, Scott will need to secure the support of more voters than former U.S. House Rep. Debbie Mucarsel-Powell, the Democratic nominee.

One complicating factor for Scott could be that voters will decide the future of abortion rights and the legality of recreational cannabis use for people over the age of 21 through two ballot questions.

The Florida state Supreme Court ruled Monday that those two questions could go before voters this November, while also saying the state’s six-week abortion ban could go into effect.

Democratic Senatorial Campaign Committee spokesperson Maeve Coyle wrote in a statement released after the ruling that the “fight against these new restrictions on access to abortion will shine a brighter spotlight on Rick Scott’s long, dangerous record of supporting draconian abortion bans.”

“In November, Florida voters will stand up for women’s freedom to make their most personal medical decisions by rejecting this abortion ban and firing Rick Scott from the Senate,” Coyle wrote.

Maryland headache for Democrats

Deciding where to spend money could also produce complications for Democrats in Maryland, where Republican nominee and former Gov. Larry Hogan has polled well compared to the two top Democratic primary candidates.

Hogan’s current favorability could “force the Democrats to spend a bit more money in Maryland that they would probably want to spend in Ohio or Montana,” Coleman said.

The odds are long against Hogan, considering that Charles M. Mathias Jr. was the last Republican to represent Maryland in the U.S. Senate from 1969 until 1987.

But a Washington Post-University of Maryland survey from early March showed voters favor Hogan by 49% over Democratic Rep. David Trone, who received 37%, and by 50% over Prince George’s County Executive Angela Alsobrooks, who received 36%.

Taylor said she’s somewhat skeptical about a poll conducted this far out from Election Day, in part because 55% of respondents said they wanted to keep the U.S. Senate under Democratic control.

“Larry Hogan’s biggest problem is that he will have an R beside his name,” Taylor said. “I think voters ultimately look at a vote for governor and a vote for Senate very differently.”