The Republican Party has reclaimed control of the United States Senate, ending two years of leadership from the Democrats.

Tuesday’s general election saw a third of the upper chamber in Congress — or 34 seats — hit the ballot, of which approximately nine were competitive.

The Democrats were vulnerable to losing their grip on the chamber, given their narrow majority. A coalition of four independent senators and 47 Democrats gave the party its 51-person majority, out of a total of 100 possible seats.

The party needed to defend every seat possible in order to retain control.

But on Tuesday, two key defeats decisively put the power over the Senate back in Republican hands.

Democratic incumbent Sherrod Brown lost his bid for reelection in the midwestern state of Ohio. Meanwhile, in West Virginia, Republicans picked up a seat formerly held by retiring independent Senator Joe Manchin.

The Republican Party also successfully defended a vulnerable seat in Texas, held by Senator Ted Cruz. Tuesday was Cruz’s second time beating back a Democratic contender angling to take his seat.

Meanwhile, in Nebraska, another Republican incumbent Deb Fischer fended off an upstart challenge from independent candidate Dan Osborn, who made the race a nail-biter in its final weeks.

The shift in control over the Senate could pave the way for Republicans to hold both chambers in Congress, which would give the party power over the legislative agenda for at least the next two years.

What happened?

Tuesday’s race to maintain the Senate was always an uphill battle for Democrats.

Under the US Constitution, the Senate has a staggered process for shaking up its ranks: Only a third of the chamber is up for reelection at any given point.

Senators serve a six-year term — much longer than the two years awarded to their counterparts in the House of Representative. That makes each seat all the more precious.

In 2022, the midterm elections resulted in a surprise upset: While Republicans were expected to maintain their lead in the Senate, they fell short when a predicted “red wave” failed to materialise. Wins in battleground states like Georgia gave Democrats the leadership.

Fast forward to 2024, and the Democrats were on the defensive. Seven of the nine toss-up races for the Senate were held by Democrats. By contrast, only two Republicans — Cruz and Fischer — were considered vulnerable.

In short, the Democrats had more to lose.

West Virginia, the first to fall

West Virginia has long been a Republican stronghold, which made the retiring Senator Manchin something of a unicorn.

Since 2000, the Appalachian state has consistently voted Republican in presidential races by healthy margins.

But Manchin — a moderate Democrat before switching to his present independent status — had been a unifying figure in the state.

The announcement in November 2023 that he would retire opened up a tantalising fight for Republicans.

Governor Jim Justice, a former Democrat turned Republican, quickly threw his hat into the ring. He won the governor’s mansion in West Virginia in 2016, the same year Republican Donald Trump took the White House, leading a wave of “outsider” candidates.

On Tuesday night, Justice — known for campaigning with a pudgy bulldog named Baby Dog — handily defeated Glenn Elliott, the Democratic mayor of the city of Wheeling.

A mighty tumble in Ohio

The defeat of three-term Democratic Senator Brown in Ohio was much more unexpected.

Ohio had, until recent years, been perceived as a swing state in the industrial Rust Belt region of the US. But as the state leaned ever rightward, Democratic leaders like Brown faced increasing threats to their positions.

By 2024, Brown was the only Democrat left holding a statewide position in Ohio.

On Tuesday, he tried to win a fourth term over Republican car dealer Bernie Moreno, a Colombian immigrant who gained Trump’s endorsement.

Brown played up his progressive bona fides and hammered Moreno over abortion policy. He also framed himself as politician willing to stand up to power, no matter the party.

“I’ve stood up to presidents in both parties,” he told local media on the campaign trail.

Moreno, meanwhile, bashed Brown as a “radical Democrat” who was lax on immigration.

In his Election Night victory speech, Moreno played up his patriotism — and echoed Trump’s call for “America First” Policies.

“Today starts a new wave. We talked about wanting a red wave. I think what we have tonight is a red, white and blue wave in this country,” Moreno said.

“Because what we need in the United States of America is leaders in Washington, DC, that actually put the interests of American citizens above all else. We’re tired of being treated like second-class citizens in our own country.”

Al Jazeera correspondent Kristen Saloomey underscored how big of a loss Ohio was for Democrats in the Senate.

“Ohio is the big flip here. This is the one that really hurt the Democrats,” she said on Election Night. “It was a really expensive race.”

More details to come.