WASHINGTON – Republicans have taken control of the US Senate.

The party will hold at least 51 seats, enough to obtain an absolute majority. The tipping point seat was Nebraska, where incumbent Republican Sen. Deb Fischer defeated her independent challenger Dan Osborn.

It is not yet clear who the next Senate majority leader will be. Republican leader Mitch McConnell, who is the longest-serving Senate leader in history, announced earlier this year that he would resign.

Senate Republicans have had the advantage this cycle, with few incumbents to protect, allowing them to challenge Democrats with hand-picked, often wealthy, recruits. Democrats were almost certain to see their narrow majority drop to at least 50-50 with Republicans with the retirement of independent Senator Joe Manchin of West Virginia.

The dome of the US Capitol is seen at dusk in Washington, DC, on November 13, 2023. (MANDEL NGAN/AFP via Getty Images)

The last time the Republican Party had a majority in the Senate was in January 2021, before Democrats took control of the Senate with a 50-50 split. In the event of a tie, the vice president can decide between Democrats, giving Democrats a one-vote majority against Vice President Kamala Harris. Democrats increased their majority to 51-49 in the 2022 midterm elections.

Here’s a look at some of this year’s key Senate races that determined the balance of power in the upper chamber:

Pennsylvania: Bob Casey versus David McCormick

The Pennsylvania Senate race between Bob Casey and David McCormack was seen as crucial to Democrats’ efforts to defend their razor-thin Senate majority.

Democratic Senator Casey, the outgoing president, once called himself a “pro-life Democrat” but changed his position on abortion rights after the The Supreme Court overturned Roe v. Wade in 2022. Casey has a strong relationship with Biden, but he has opposed the administration on some issues and supported some of Trump’s trade policies in the past. He has been in the Senate since 2007.

McCormick is a former CEO of Bridgewater Associates, one of the world’s largest hedge funds, and served as deputy national security advisor for international economic affairs under former President George W. Bush.

Wisconsin: Tammy Baldwin vs. Eric Hovde

The Wisconsin Senate race between Democratic incumbent Sen. Tammy Baldwin and Republican Eric Hovde was considered the toughest political environment of all three of Baldwin’s races.

Baldwin has been an advocate in politics since 1986. She served in the United States House of Representatives before being elected to the Senate in 2012.

Hovde is a multimillionaire and CEO of Hovde Properties, a real estate company founded by his grandfather in 1933.

Ohio: Sherrod Brown vs. Bernie Moreno

Democratic Sen. Sherrod Brown, the incumbent, is in a hotly contested re-election race against Republican candidate Bernie Moreno.

RELATED: Ohio Senate race between Sherrod Brown and Bernie Moreno: What you need to know

Brown is the only elected official from Ohio, an increasingly red state. His campaign aimed to attract independent and crossover Republican voters in a record-breaking race worth more than $400 million.

Moreno, supported by Donald Trump, is a wealthy Colombian-born businessman and owner of a Cleveland car dealership.

Maryland: Larry Hogan vs. Angela Alsobrooks

Maryland Senate race among alumni Governor Larry Hogan and Prince George’s County Executive Angela Alsobrooks fills the seat of incumbent Democratic Sen. Ben Cardin.

Hogan is a two-term governor who enjoyed great popularity while serving in statewide office. He publicly opposed former president Donald Trump and said he never voted for him, although Trump supported Hogan in the Senate race.

Alsobrooks prioritized abortion rights during his campaign and described Hogan’s actions in office as proof that he failed to defend a woman’s right to choose.

Montana: Jon Tester vs. Tim Sheehy

Sen. Jon Tester, the incumbent Democratic senator from Montana, faced his toughest race yet against Republican Tim Sheehy, a millionaire businessman and former Navy SEAL.

Senate Republicans viewed Montana as their best chance to unseat a Democrat, but Tester is a popular figure in the Big Sky state, where more than $238 million has been spent on advertising.

Sheehy was leading in the polls, but he also faced scrutiny after claiming he was shot in the arm during a firefight in Afghanistan. A Glacier National Park ranger came forward and said Sheehy accidentally shot himself in 2015 while traveling with his family and his gun fell out of a vehicle and was fired in a parking lot in Logan Pass.

Florida: Rick Scott v. Debbie Mucarsel-Powell

Republican Sen. Rick Scott, the incumbent, faced former Rep. Debbie Mucarsel-Powell in the Florida Senate race.

Scott, a former governor and close ally of Donald Trump, was seeking a second term in the Senate. He said he intends to run for Senate Republican leader when Mitch McConnell leaves office.

Mucarsel-Powell was the first South American-born immigrant elected to Congress, according to the House website. She served one term before losing to Republican U.S. Rep. Carlos Gimenez in 2020.

Texas: Ted Cruz vs. Colin Allred

The Texas Senate race between Republican Sen. Ted Cruz, the incumbent, and Democratic U.S. Rep. Colin Allred, was one of the only races where a Republican senator is in a competitive race.

Allred, a former NFL player who broke with his party over President Joe Biden’s handling of the US-Mexico border, was still considered the underdog against Cruz: It’s been 30 years since Democrats won a statewide race in the Lone Star State.

Arizona: Ruben Gallego vs. Kari Lake

Democratic U.S. Rep. Ruben Gallego and former TV anchor Kari Lake, a Republican, were racing to replace outgoing independent Arizona Sen. Krysten Sinema, who is not seeking re-election.

Gallego, a retired Marine and longtime congressman who represents the greater Phoenix area, was considered the favorite.

Lake became the darling of populists just after leaving her career as a local TV news anchor and running for governor in 2022. She lost to Democrat Katie Hobbs.

West Virginia: Jim Justice v. Glenn Elliott

West Virginia U.S. Senate race between Gov. Jim Justice and Wheeling Mayor Glenn Elliott Democrats were widely expected to lose the seat held by Sen. Joe Manchin for 14 years.

Manchin, 76, was the only Democrat to hold statewide office in West Virginia before leaving the party in May and registering as an independent.

RELATED: West Virginia Senate race between Jim Justice and Glenn Elliott: What you need to know

Justice, 73, has been governor of West Virginia since 2017. Justice and his family own dozens of businesses and are worth more than $1.5 billion, according to Forbes. He held a double-digit lead in all polls leading up to Election Day.

Elliott, 52, is an attorney who has served as mayor of Wheeling since 2016.