All eyes seem glued on the United States presidential race, as former President Donald Trump attempts to eke out a victory over Vice President Kamala Harris.

But as both candidates strive to pull ahead in the nail-biting race, other contests are set to unfold across the country, with the balance of power at stake.

The general election on November 5 will not only decide the next president but also which party controls the two chambers of Congress: the Senate and the House of Representatives.

Right now, Congress is split. The Republicans lead the House, while the Democrats hold the Senate.

But many political analysts speculate the Senate could be on the verge of flipping to Republican control this election cycle, making its races ones to watch.

There are 100 seats total in the Senate, a third of which are up for grabs every two years. Democrats and allied independents currently claim 51 seats — a narrow lead that could easily be lost.

Thirty-four Senate seats are up for a vote this election year. Of those, eight races are considered tightly competitive.

And the odds are not on the Democrats’ side. Seven of those eight embattled seats are currently occupied by Democrats. Only one Republican-held seat is considered up for grabs.

Ultimately, whoever controls Congress controls the ability to pass legislation, among other powers. And that could buoy or doom any incoming president’s agenda.

So whose Senate seats could switch sides? Check out which states are in the hot seat below.

Montana

Control of the Senate may come down to Montana, a sprawling, largely rural state in the north with a population of just 1.1 million.

Montana Democrat Jon Tester has held his seat in the US Senate for three terms, but the farmer-turned-politician has repeatedly faced punishing challenges in the solidly red state.

The state is considered a strong base of Republican support. Montana, for instance, has consistently voted for Republican presidential candidates since 1968, save for a narrow victory by Democrat Bill Clinton in 1992.

Montana State University political scientist Jessi Bennion has described Tester as a “unicorn” — a rare Democrat to succeed in a statewide vote. But Bennion warns he could also be a dying breed.

“He was a farmer. He was a rural Democrat, the last rural Democrat,” Bennion told The Associated Press news agency.

Tester’s challenger this election cycle is former Navy SEAL and businessman Tim Sheehy, a Trump-backed Republican candidate.

Recent polls show Sheehy leading as November’s vote approaches. Analysts like Bennion note that Sheehy’s numbers have been bolstered by economic and social trends.

For example, the growth in Montana’s population, fuelled by the tech industry and tourism, has contributed to a cost-of-living crisis and increases in housing prices across the state.

That has eaten into Tester’s support among unions and in Montana’s more liberal pockets.

Wisconsin

Wisconsin used to be part of the Democrats’ “blue wall”: a group of states that voted consistently for the left-leaning party.

But over the last eight years, the state has become one of the most coveted swing states in the country.

Democrat Tammy Baldwin came to power during the “blue wall” years. Since she was 24 years old, she has been politically active in the midwestern state: Her first elected office was on the Dane County Board of Supervisors in 1986.

She went on to join the US House of Representatives in 1999, as the first woman to represent the state in Congress. Then, in 2012, she also became the first openly gay person elected to the US Senate.

She has touted herself as a reliably progressive member of the party and comfortably won re-election in 2018.

But this year’s election is a different story. Her early lead in the polls has evaporated as November’s election day nears.

She faces Republican Eric Hovde, a millionaire banking executive. Hovde has poured millions of dollars of his own money into the race and has attacked his Democratic rival for government spending and inflation. He has also called for the US-Mexico border to be closed.

Baldwin, meanwhile, has sought to position herself as the candidate with experience, compared with Hovde, who has never held public office.

Ohio

Senator Sherrod Brown is another Democrat in an increasingly red state: Ohio.

Each state has two seats in the US Senate, and in 2022, during the last election cycle, the tight nature of Ohio’s races was on full display, as political newcomer JD Vance won a competitive race for Ohio’s second Senate seat.

Senator Vance is now Trump’s running mate on the Republican presidential ticket.

In contrast to the freshman Ohio senator, Brown is a longtime Ohio politician who served in state government before being elected to the US House and later the Senate.

The Democrat has cultivated a populist, pro-union reputation, cutting a professorial figure in his often-wrinkled suits.

Brown first reached the Senate in 2006, defeating a two-term Republican incumbent. But now Brown himself is the incumbent, and polls show him vulnerable to his Republican challenger, Bernie Moreno, a Colombian immigrant and car dealership owner.

Moreno has Trump’s backing, and Ohio has leaned increasingly Republican in recent years. Brown is considered the only Democrat to hold a statewide elected office.

Moreno and Brown are currently neck and neck: A Washington Post poll in October found that 48 percent of the voters surveyed backed Brown, versus 47 percent for Moreno.

Adding to the pressure is the national spotlight on Ohio. Republicans like Trump have used the state — and the city of Springfield in particular — as an example of the supposed threats immigration poses.

But Brown has sought to draw bipartisan support. “I’ve stood up to presidents in both parties,” he told local media in August.

In the final days of the race, Brown has also seized on cellphone footage showing Moreno criticising women over 50 who support abortion access.

“I’m thinking to myself, ‘I don’t think that’s an issue for you,’” Moreno can be heard saying in the recording.

Nevada

The battle for the Senate mirrors the battle for the presidency, in that swing states will hold disproportionate weight.

This is true of Nevada, a state considered to have a roughly even amount of Democrats and Republicans.

That makes its latest Senate race a squeaker. The incumbent Democrat Jacky Rosen was first elected in 2018, when she ousted the Republican who previously held the seat.

Now, it is her turn to play defence, as she attempts to fend off Republican candidate Sam Brown.

Brown is a veteran who served with the US military in Afghanistan, where he suffered severe burns from an improvised explosive device. He subsequently received a Purple Heart, an honour given to those killed or wounded in combat.

Trump has given Brown his stamp of approval, but other Republicans in the state have criticised him for his lack of grassroots campaigning.

Rosen, meanwhile, has sought to highlight Brown’s past opposition to abortion and his affiliation with Trump’s “Make America Great Again” (MAGA) movement.

A TV advertisement her campaign produced called Brown “another MAGA extremist trying to take away abortion rights”.

Pennsylvania

Another swing state that could determine the makeup of the Senate is Pennsylvania, part of the mid-Atlantic region of the US.

There, Democratic incumbent Bob Casey is aiming for a fourth term representing the Keystone State.

A lawyer and son of a former governor, Casey is a veteran of the state’s political sphere. But seeking to knock him off his perch is David McCormick, a former hedge fund CEO who worked in the administration of Republican President George W Bush.

McCormick has attempted to paint Casey as a career politician out of touch with everyday Pennsylvanians.

“I’m not going to take any preaching from a guy who spent 30 years in public office and hadn’t gotten much done,” the Republican said at a recent debate.

He has also highlighted inconsistencies in Casey’s stance towards issues like abortion access.

Casey, meanwhile, has underscored McCormick’s resistance to firearm regulations and his investments in Chinese companies. The race, Casey said, boils down to “my work in the United States Senate and his work as a hedge fund CEO”.

Michigan

Michigan Democrat Debbie Stabenow set off a bombshell in 2023, when she announced her plans to retire once her current term expired.

That meant a seat in the Senate would open up — with no incumbent to defend it.

In the months since, a tight race has unfolded in the midwestern state of Michigan, which has pivoted between Republican and Democratic candidates in recent years.

Democrats hope Elissa Slotkin, currently a member of the House, can hold onto the seat for the party.

Slotkin formerly worked with the Central Intelligence Agency (CIA) and the Department of Defense, and she has touted her national security background as a source of bipartisan appeal.

Her challenger is Mike Rogers, a former congressman and CNN national security analyst. He is attempting to become the first Republican to win a Senate seat in Michigan in 30 years, with Trump’s backing.

Rogers too has attempted to appeal to Michigan’s “purple” voters, saying in a recent debate that he “will look for every opportunity to be bipartisan”.

Arizona

Another retirement, this time in Arizona, has also opened up a battleground for the Senate.

In March, Senator Kyrsten Sinema announced she would not seek re-election in November, after a tumultuous six-year term in the chamber.

The first female senator from Arizona, Sinema started out as a moderate Democrat in 2019, but after breaking with her party on several key votes, she rebranded as an independent in 2021.

Now, her absence on the ballot has left an undefended seat up for grabs. Democrat Ruben Gallego, a former US marine, and Republican Kari Lake, who was once a television anchor, are vying for her spot.

Lake has gained nationwide prominence as a vocal advocate of Trump’s false claims that the 2020 presidential election was marred by fraud.

She has deployed similar arguments in her own political career: When she lost the 2022 gubernatorial race, she likewise challenged her defeat and cast doubt on the result.

Gallego, on the other hand, currently serves in the House — and he has framed himself as a fiery progressive critic of both right-wing and centrist figures like Sinema.

Polls for weeks had shown a comfortable lead for Gallego, but the race has tightened as November 5 approaches.

Texas

Republican firebrand Ted Cruz is the only member of his party facing a tough road to re-election in the Senate this year.

Cruz hails from Texas, a deep-red state known for its right-wing politics. But Democrats have long perceived Cruz’s seat as vulnerable to a shake-up, and they are mounting a campaign to jettison the incumbent.

Texas’s shifting demographics are weighing in the Democrats’ favour: The state has seen its population boom, particularly in its left-leaning urban areas.

Add that to Cruz’s unique ability to alienate both liberals and members of his own party, and you’ll find an incumbent poised for an upset — or so Democrats hope.

But Cruz has nevertheless shown an ability to withstand challenges. First elected as a far-right Tea Party candidate in 2012, Cruz was up for re-election in 2018 when Democrats similarly mounted a campaign to topple him.

Their candidate that year was Beto O’Rourke, a US representative. While the race was tight, Cruz nevertheless beat O’Rourke at the ballot box.

This year, Cruz hopes to do the same with former NFL player and civil rights lawyer Colin Allred, who has stepped forward as the Democrats’ latest hope.

Allred, currently a member of Congress, has tacked to the right on several issues, including immigration policy. Despite Democratic money pouring in to boost Allred, Cruz is still widely seen as having the edge.