Balance of power: With several races still undecided, Senate control remains at a deadlock

Control of the Senate was still up in the air Thursday as Republicans beat Democratic challengers in crucial states but failed to lock down the seats needed to retain their tenuous Senate majority.

One race in Georgia is headed to a January runoff. A second contest in Georgia and races in North Carolina and Alaska remain undecided, leaving the chamber now deadlocked 48-48. An outcome may not be known until the new year.

With the presidential race between President Donald Trump and Democrat Joe Biden also undecided, the Senate is in limbo because the vice president of the eventual winner's party would serve as a tie-breaker in a split chamber.

“We’re waiting — whether I’m going to be the majority leader or not,” Senate Majority Leader Mitch McConnell, R-Ky., said Wednesday.

That was still the case Thursday.

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There already is a Jan. 5 runoff in the state's other Senate race. GOP Sen. Kelly Loeffler will face Democrat Raphael Warnock, a Black pastor at the church where the Rev. Martin Luther King Jr. preached, after they emerged as top vote-getters, but failed to clear the majority threshold.

Republicans were confident they would keep Alaska, where GOP Sen. Dan Sullivan was challenged by newcomer Al Gross, a doctor and Democratic-backed independent.

Democrats faced long but not fully impossible odds to take a slim majority after a disappointing election night when Republicans defeated multiple challengers.

In Michigan, Democrats were spared a loss when Sen. Gary Peters withstood a strong challenge from Republican John James, a Black Republican businessman. But Republicans held on to Susan Collins in Maine and other key seats.

McConnell, who secured a seventh term for himself in a costly campaign against Democrat Amy McGrath, a former fighter pilot, has said he he felt “pretty good” about the remaining contests.

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Election night jarred Democrats and enthusiastic backers who were eager to counter Trump and his party’s grip on the Senate.

While Democrats picked up must-win seats in Colorado and Arizona, they suffered a setback in Alabama, and Republicans held their own in one race after another — in South Carolina, Iowa, Texas, Kansas and Montana. That dramatically limited Democrats' hopes to make inroads.

Many races attracted an unprecedented outpouring of small-dollar donations for Democrats.

Key U.S. Senate races

Arizona

Former astronaut and Democrat Mark Kelly defeated incumbent Republican Sen. Martha McSally, flipping a critical Senate seat. An October poll from Marist College had Kelly ahead with 52% of likely voters and McSally with 46% of likely voters.

RELATED: Arizona's Senate race has Martha McSally, Mark Kelly campaigning days before Election Day

Kelly was pitched by Democrats as a centrist in one of the country’s most expensive campaigns. He will finish late Sen. John McCain’s term, which ends in 2022. McSally was appointed to the seat by Gov. Doug Ducey after she was defeated by Kyrsten Sinema in the 2018 election for the seat that was vacated by Jeff Flake.

Arkansas

Republican Sen. Tom Cotton of Arkansas easily won reelection, and many political experts said his race has allowed him to lay the groundwork for a potential 2024 White House bid.

The 43-year-old Cotton defeated Libertarian nominee Ricky Dale Harrington, a former prison chaplain who had never run for office. The only Democrat who was running against Cotton dropped out hours after the filing deadline last year.

Colorado

FOX News projected that Colorado flipped its Senate seat to blue, handing former Gov. John Hickenlooper a victory over Republican incumbent Cory Gardner.

Georgia

The Peach State was in a unique position this political cycle with both a regularly scheduled Senate race and a special election.

The counting continued in Georgia, where GOP Sen. David Perdue was trying to hold off Democrat Jon Ossoff in a multi-candidate race that could also go to a runoff if neither candidate clears the 50% threshold to win.

FOX News is reporting Georgia's special election will head into a runoff between Incumbent Republican Kelly Loeffler and Democrat Raphael Warnock after neither received more than 50% of the vote.

The Senate seat was vacated after Sen. Johnny Isakson announced his resignation last year. Republican Gov. Brian Kemp appointed Kelly Loeffler to serve out the remainder of Isakson’s term.

RELATED: Perdue vs Ossoff: Battle for Georgia US Senate seat

Iowa

Iowa incumbent Republican Sen. Joni Ernst defeated Democrat challenger Theresa Greenfield in one of the most contested races of the 2020 campaign.

Ernst won more than 786,000 votes, or 51.5%, with 93% of the results in. Greenfield received more than 693,000 votes.

The race between Ernst and Greenfield, a real estate developer, was tight throughout with the Republican senator pulling ahead in the week leading up to the election, FOX News reported.

A recent poll from Emerson College had Ernst with 46% of likely voters and Greenfield with 45%. A New York Times/Siena College poll had 45% of likely voters supporting Ernst and 44% of them supporting Greenfield.

Maine

Incumbent Republican Sen. Susan Collins may avoid a runoff with Independents Lisa Savage and Max Linn after Democrat Sarah Gideon conceded Wednesday.

The outcome, announced on Wednesday, a day after voting ended, gave the 67-year-old incumbent a fifth term in office and dealt another blow to Democrats' hopes for taking control of the GOP-led U.S. Senate.

Montana

In Montana, Incumbent Republican Sen. Steve Daines won and kept his seat in a tight race against Democratic Gov. Steve Bullock.

Recent polling showed both men practically had an equal chance of winning. Montana State University Billings released an October poll showing Bullock winning 48% of likely voters and Daines winning 47%.

Fundraising efforts also reflected the competitiveness of the race. According to the Associated Press, Bullock raised $28 million in the third quarter, the most for any Montana statewide candidate in a single three-month period. Daines raised $11.5 million in the same timeframe.

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North Carolina

Incumbent Republican Sen. Thom Tillis faces Democratic challenger Cal Cunningham. Recent polls suggested Cunningham was headed to victory. The University of Massachusetts Lowell had Cunningham winning 49% of likely North Carolina voters and Tillis with 45%.

Cunningham did well in fundraising, bringing in $28 million in the third quarter, more than any other North Carolina politician, according to his campaign. The Associated Press reported that Tillis raised $6.6 million in the same time period.

South Carolina

Incumbent Republican Sen. Lindsey Graham fended off a challenge by Democrat Jaime Harrison, retaining his seat in a narrow race, according to a race projection by FOX News.

Graham, 65, will enter his fourth term after first being elected to the U.S. Senate in 2002. He currently serves as the chairman of the Senate Judiciary Committee.

Graham also surpassed a record. The Associated Press reported in October that Graham raised $28 million in the third quarter, more than any other Republican Senate candidate. But he admitted to FOX News last month that he was being “killed financially” compared to Harrison’s campaign portfolio.

Key U.S. House races

Democrats currently have 208 seats in the House, while the GOP has 191 seats. Political insiders believe the Democrats will most likely expand their control, according to FOX News.

Here are some races to keep tabs on as more districts report results:

California- 21st Congressional District

It was a rematch between Incumbent Democrat TJ Cox and Republican David Valadao. A FOX News tally showed Valdado with 51.38% of the votes and Cox with 48.62% with 42.36% of votes reported. Cox beat out Valadao in 2018.

Georgia- 14th Congressional District

GOP candidate Marjorie Taylor Greene, who has publicly supported the QAnon conspiracy theory, won in the solidly Republican district with 75% of the total vote, according to FOX 5 Atlanta. Her Democratic challenger, Kevin Van Ausdal, dropped out of the race, citing personal reasons. Greene will be replacing Republican Tom Graves, who resigned on Oct. 4.

New Jersey- 2nd Congressional District

Incumbent Republican Jeff Van Drew faces Democrat Amy Kennedy. So far, Drew holds 51.52% of the vote, with Kennedy at 46.86% and 74.95% of votes reported.

New York- 16th Congressional District

With no Republican filing for candidacy, Jamaal Bowman won New York’s 16th Congressional District seat on Election Day. During the Democratic primary, he beat out incumbent Eliot Engel.

The Associated Press called the race for Bowman, who beat Conservative Party candidate Patrick McManus, a retired firefighter.

There was no Republican on the district’s ballot, which includes part of the Bronx and lower Westchester County. During the campaign, Bowman spoke about growing up Black in public housing, being beaten by police officers at age 11, becoming a teacher and then a principal deeply involved in education reform.

New York- 11th Congressional District

Incumbent Democrat Max Rose is behind Republican Nicole Malliotakis by a small margin with Rose holding 42% of the vote and Mallliotakis with 58%, and 95% of precincts have reported so far.

New Mexico- 2nd Congressional District

Republican Yvette Herrell won election to the U.S. House in New Mexico’s 2nd Congressional District, beating incumbent Rep. Xochitl Torres Small, who tried to hold on to her seat.

The race was a rematch, as Torres Small formerly ran against Herrell, defeating her by an extremely narrow margin of less than 4,000 votes.

The district traditionally leans Republican, and Trump won the district by 10 points in 2016 over Hillary Clinton.

North Carolina- 11th Congressional District

Republican Madison Cawthorn was called as the winner of the U.S. House seat in western North Carolina Tuesday that was vacated by White House Chief of Staff Mark Meadows.

Cawthorn, 25, becomes the youngest member elected to Congress since the late 1700s.

The candidate -- who first catapulted to GOP stardom after speaking at the Republican National Convention in August, getting up from his wheelchair at one point on stage -- defeated incumbent U.S. Rep. Moe Davis, D-N.C., to capture the 11th Congressional District seat, according to the Associated Press.

Minnesota- 7th Congressional District

Republican Michelle Fischbach won the election to the U.S. House in Minnesota's 7th Congressional District, beating incumbent Rep. Collin Peterson, who hoped to keep his seat.

Peterson had withstood a Republican wave before, but political insiders believed this was going to be his toughest fight yet given that his district was turning deep red — and they were right.

Peterson, the chairman of the House Agriculture Committee, was seeking his 16th term.

Oklahoma- 5th Congressional District

According to the Associated Press, Republican Sen. Stephanie Bice defeated Incumbent Democrat Kendra Horn.

Bice, 46, earned a reputation as a political moderate in her two terms in the Senate, writing a series of bills to help overhaul the state’s antiquated alcohol laws and inviting a Hindu leader to deliver a prayer after the Legislature faced criticism for its lack of religious diversity.

The Associated Press contributed to this report.