With their control of the Senate in the balance in the upcoming election, Democrats kicked off 2024 by announcing an eight-figure influx of cash backing incumbents in two red states: Sen. Sherrod Brown in Ohio and Sen. Jon Tester in Montana.

The move comes as the 51-49 seat majority commanded by Sen. Chuck Schumer, D-N.Y., grows increasingly threatened in an election year where nearly all the competitive seats are held by Democrats.

Brown’s home state of Ohio voted for former President Donald Trump 53-45% over now-President Joe Biden in 2020, while Tester’s native Montana voted for Trump 57-41%. Both candidates are the only Democrats elected statewide in their respective states.

The Democratic Senatorial Campaign Committee says the funding will pay for staff dedicated to field organizing, training volunteers, campaign data and analytics, and “building meaningful outreach to communities of color and specific constituencies.” The DSCC did not publicize a specific number, only noting it was north of $10 million.

Ultimately, the announced investment will likely represent only a fraction of the campaign, committee and super PAC spending on the Senate this year: over $2 billion was spent on just the top-10 most expensive Senate races in 2022, a non-presidential election year, according to OpenSecrets.

“The DSCC’s investments in sustained, effective grassroots organizing will lay the groundwork for our campaigns to win tough races,” said DSCC Chair Gary Peters, a senator from Michigan, in a statement on Monday. “This election will determine the future of our country, and we look forward to joining with voters, volunteers and community leaders to defend Democrats’ Senate majority.” 

Democrats' majority in the Senate is on shaky footing in part because of Sen. Joe Manchin, D-W.Va., opting to give up his seat and the decision by Arizona Sen. Krysten Sinema to leave the Democratic Party, potentially setting up a three-way race. West Virginia is among the reddest states in the nation.

Vice President Kamala Harris is empowered to cast the deciding ballot on 50-50 ties, meaning if Biden and Harris can hold onto the White House, Democrats would only need to win 50 seats to keep Schumer in the majority leader’s office. In 2022, Democrats held onto every seat up for reelection and picked up a Republican-held seat in Pennsylvania with John Fetterman’s victory.

Brown has been focusing on boosting his working class bonafides, tying himself closely to labor unions and opposing trade deals supported by Biden that he says would hurt American workers.

Tester is campaigning on affordability, infrastructure and investing in — and protecting the environment and economies of — the agricultural communities that make up his state. He also frequently emphasizes his Montanan credentials and rural background. 

“I'm the Senate's only working dirt farmer. I lost three fingers in a meat grinding accident when I was younger. I get a $12 flattop haircut. Most of my shirts are stained with dirt,” Tester posted on X, the platform formerly known as Twitter, last week. On Sunday, he posted a picture of himself next to the meat grinder he said stole his fingers as a kid, noting he still uses it because “it’s a good meat grinder.”

“Montana til I die,” he wrote in another post last month.

Tester is in a fight for his political life, as his fellow Montana Sen. Steve Daines has been tasked with ending it. As chair of the National Republican Senatorial Committee, Daines has overseen attacks on Tester for being “soft on China” and his support of the Biden administration’s agenda — one recent poll had Biden’s support at 28% in the state. And the Montana Republican backed Tim Sheehy, a businessman and retired Navy SEAL, to challenge Tester.

“The Democrats are going to make this the most expensive race in American history per vote… in Montana, of all places, and they're gonna pour so much money in behind John Tester, they already are, it's going to take a team effort from the Republican side to win this race,” Sheehy said on Fox News last month. “We're gonna have to work as a team, which sometimes is not what Republicans do. Sometimes we fight each other. It's time for us to work as a team, win this race, we conservative control of the U.S. Senate, because the next decade of this country hinges on this race.”

An Emerson College poll of Montana voters in October found Tester leading Sheehy 39% to 35%, though the difference was within the survey’s margin of error and another 21% said they were undecided. Montana's primaries are set for June 4. 

The elections forecaster Cook Political Report moved the race from a “lean Democrat” categorization to “toss up” in November. Brown’s campaign and the Arizona contest are the only two other 2024 Senate races ranked as a toss up by Cook Political Report.

Brown will face the winner of a crowded Republican primary that includes the Trump-backed Cleveland businessman Bernie Moreno, Ohio Secretary of State Frank LaRose and state Sen. Matt Dolan, who hails from the family that owns the Cleveland Guardians baseball team. Moreno and Dolan previously ran in the 2022 primary, losing to eventual victor J.D. Vance, who has backed Moreno this time around.

On Monday, Moreno announced an endorsement from Rep. Jim Jordan, R-Ohio, with the powerful House Judiciary Committee chair dubbing him “a true America First conservative” and a “common sense conservative fighter.” 

Publicly available polling from last year consistently showed Brown with leads over all three of his potential challengers in hypothetical head-to-head matchups. Republican voters in Ohio will make their pick on March 19.

In Arizona, where Sinema has yet to reveal her plans, Democratic Rep. Ruben Gallego announced his campaign raised $3.3 million in the last quarter of 2023, outpacing the $2.1 million raised by Republican Kari Lake, an election denier who narrowly lost the governor’s race in 2022. Gallego’s campaign said he’s raised $13 million in the last year and has stashed away $6.5 million to spend heading into 2024. Quarterly campaign reports for Senate candidates are due to be submitted at the end of the month.

“In a three-way race, as an independent, it’s a difficult path in the polling that we have looked at. Everything we’ve seen shows there is not a real clear path for Sinema,” Daines told CNN over the weekend.

Lake has not officially been backed by national Senate Republicans, but her campaign is arguing she’s in the best position to represent the party in November. 

“Kari Lake is outworking everyone, posting a very strong fundraising haul for her first quarter in the race. Arizona is the best pick up opportunity for Senate Republicans,” Garrett Ventry, a senior adviser to Lake, said in a statement to Politico.

Elsewhere on the Senate map, Republican candidate David McCormick — who lost to TV doctor Mehmet Oz in the 2022 Pennsylvania Senate primary — has raised $5.4 million to take on Democratic Sen. Bob Casey, whose campaign has yet to publicize his most recent fundraising totals. And Nevada Republican Sam Brown, seeking to unseat Democratic Sen. Jacky Rosen, says he raised $1.85 million in the fourth quarter of 2023.