Democrats need to pick up four seats from Republicans to win control of the 100-seat Senate in the midterm elections on November 3.
While voters will pick candidates in 35 states, independent analysts only see nine of those races as competitive.
Most of these contests take place in states that President Donald Trump won in 2024, but his approval rating stands at 33 percent, the lowest of his political career, according to Reuters/Ipsos polling.
Alaska
Incumbent Republican Senator Dan Sullivan faces two liabilities in his reelection campaign: a credible challenge from a Democrat and another person on the ballot with the same name.
Democrat Mary Peltola previously held the state's sole House seat for a single term and has campaigned as a centrist. She garnered 82,000 votes to Sullivan's 69,000 in the state's nonpartisan primary in August, in what could be an ominous sign for the incumbent.
Sullivan also will have to contend with another Republican, retired teacher Dan J. Sullivan, who got enough votes to advance to the November election despite Republican attempts to knock him off the ballot.
Peltola could also benefit from the state's ranked-choice voting system, which takes voters' second choices into account.
Polling has been sparse in this race, but analysts see it as a toss-up.
Georgia
Democratic Senator Jon Ossoff is running for reelection against Republican Representative Mike Collins, a conservative backed by Trump.
Georgia has emerged as a top battleground state. Trump narrowly won the state in 2024, while Ossoff, 39, narrowly won his seat in a 2021 runoff. Analysts see him as a possible 2028 presidential candidate.
In recent weeks, Collins has been under scrutiny for racist posts by a former aide, which his campaign has disavowed.
Most polls have shown Ossoff leading Collins, and nonpartisan analysts say he currently holds the advantage in this race.
Iowa
After a decade of Republican dominance, Iowa is home to competitive races this year, as the farm state struggles with high fuel prices.
Representative Ashley Hinson aims to keep the seat in Republican hands following the retirement of incumbent Senator Joni Ernst.
She faces state representative Josh Turek, a former Paralympic basketball player who has emphasised his bipartisan work in the state legislature.
Polls show a close race, and analysts say it should be one of the most competitive contests this fall.
Maine
Democrats scrambled in July to find a replacement for Graham Platner, the progressive oyster farmer and political newcomer who dropped out after facing accusations of sexual assault, which he denied. The party quickly coalesced around Troy Jackson, a former lumberjack and state legislator who shares Platner's progressive politics.
Jackson, 58, takes on incumbent Republican Senator Susan Collins, a moderate who occasionally breaks with her party.
First elected in 1996, Collins has won reelection easily even as the northeastern state has consistently backed Democratic presidential candidates.
Recent polls have shown Jackson holding a three- to four-percentage-point lead.
Michigan
Democrats are playing defence in Michigan, where they hope to retain the seat held by retiring Senator Gary Peters. A loss in this closely contested state would complicate their efforts to win control of the chamber.
Democratic nominee Abdul El-Sayed, a progressive, faces lingering skepticism as he tries to consolidate support after narrowly defeating centrist Representative Haley Stevens in a bitter primary.
He faces Republican Mike Rogers, a former House member who lost a Senate race in 2024.
Polls show a close race, and nonpartisan analysts rate it a toss-up, saying El-Sayed's left-wing candidacy could give Rogers a greater opportunity to win independent voters.
New Hampshire
Republican John Sununu is running to return to the Senate, where he previously served from 2003 to 2009, while Democrats have nominated Representative Chris Pappas for this open seat.
Nonpartisan analysts say Pappas holds the edge.
North Carolina
Democrats have a good chance to pick up a seat in North Carolina, where incumbent Republican Senator Thom Tillis is retiring.
Opinion polls show former Democratic Governor Roy Cooper holding a steady lead over Republican operative Michael Whatley, a Trump ally who most recently chaired the Republican National Committee.
Cooper is well known to North Carolina voters, having won four races as state attorney general and two more as governor in 2016 and 2020, even as Trump carried the state in those years.
Whatley also has decades of experience in politics but has not previously run for office.
Ohio
Former Democratic Senator Sherrod Brown is hoping voters in Ohio remember his long record of economic advocacy as he tries to win back his old job.
First elected in 2006, Brown was defeated by Republican Bernie Moreno in 2024, a year when Trump won the once-competitive state by 11 percentage points.
He is now trying to unseat incumbent Republican Senator Jon Husted, who was appointed to the seat in 2025 after then-Senator JD Vance resigned to serve as Trump's vice president. Husted previously served as lieutenant governor and secretary of state.
Ohio has trended steadily Republican over the past decade, but recent polls show Brown leading Husted by three to four percentage points and analysts view the race as a toss-up.
The winner of this race will serve the remainder of Vance's term, through January 2029.
Texas
This Republican-dominated state has emerged as a surprise battleground this year. Polls show a close race between Democrat James Talarico, a state representative and former seminary student, and Republican Ken Paxton, the state's attorney general.
Despite allegations of marital infidelity that nearly forced him from office in 2023, Paxton unseated incumbent Senator John Cornyn with Trump's backing in a divisive primary. Since then, he has struggled to raise money — forcing his party to spend money shoring up what would normally be considered a safe seat.
Talarico has sought to win over independents and disaffected Republicans. Analysts see this race as a toss-up.
