WASHINGTON — In a night of close electoral race, the chances of Democrats flipping enough seats to take control of the Senate appeared to be dwindling early Wednesday as Republicans beat off challenges in a number of key races.

Democrats need at least three wins — four if former Vice President Joe Biden does not win the presidential race — to take control of the chamber. But Republicans came out on top in several battleground states. Two Democratic wins came out West.

In Colorado, the state's former governor, John Hickenlooper, defeated incumbent Republican Sen. Cory Gardner. And in Arizona, Democratic challenger Mark Kelly defeated Republican Sen. Martha McSally. A win for Kelly, a retired astronaut and husband of former Rep. Gabby Giffords, was critical for Democrats.

But in the South, Republicans flipped a seat, taking out vulnerable incumbent Sen. Doug Jones in Alabama. More than a dozen competitive races will determine which party controls the upper chamber come January. Several other wins will be needed for the chamber to switch hands into Democratic control.

Republicans continued to see big wins throughout the night, holding off liberal challengers in Iowa, Montana, South Carolina and a longshot race challenging Senate Majority Leader Mitch McConnell.

In North Carolina, eyed as one of the key races determining whether Democrats will take control of the chamber, votes were still being counted and no winner had been officially called, but incumbent Republican Sen. Thom Tillis declared victory.

There were 35 Senate seats up for grabs going into Election Day, but only about 14 were truly in play. Democrats would need a net gain of three or four seats to flip control of the Senate, depending on whether Republicans or Democrats win the White House. Republicans currently hold 53 seats, while Democrats have 45, plus two independents who caucus with them.

Both parties have so far flipped a seat: Alabama Democratic Sen. Doug Jones lost to former Auburn football coach Tommy Tuberville in a state Trump dominated. And former Gov. John Hickenlooper defeated Republican Sen. Cory Gardner in Colorado, where Biden also triumphed over Trump.

In Maine, state House speaker Sara Gideon is trying to oust Sen. Susan Collins, the last Republican member of Congress in New England. Since her first victory in 1996, Collins developed a Maine-centric, independent image, winning her last election with nearly 69% of the vote.

But her approval fell during the Trump era, due in part to her support of the 2017 GOP tax plan and the nomination of Judge Brett Kavanaugh to the Supreme Court. Polls this fall show her behind in the race, as attack ads portray her as beholden to special interests.

But the race for the Senate could come down to North Carolina, where Biden has established a slim advantage, according to a recent CNN poll.

In another victory for the GOP, Republican Sen. Steve Daines will hold onto his seat, CNN projects, defeating Gov. Steve Bullock. National Democrats had pushed for Bullock, the state's two-term Democratic governor, to run, believing he would make a formidable challenger. His entry into the race made it a competitive contest, but ultimately, he came up short, conceding the race to Daines early Wednesday morning.

At a rally in Kentucky on Monday, Senate Majority Leader Mitch McConnell won his own re-election on Tuesday, defeating Democratic opponent Amy McGrath.

Georgia GOP Sen. Kelly Loeffler's race will go to a runoff between her and Democrat Raphael Warnock, the senior pastor of the Ebenezer Baptist Church in Atlanta. In the unusual melee election, the appointed senator faced multiple candidates, including GOP Rep. Doug Collins, who targeted the same swath of conservative voters as she did.

Republicans hope that John James, a Republican businessman who flew Army helicopters in the Iraq War, can defeat Michigan Democratic Sen. Gary Peters and become the state's first Black senator. But Peters led in the polls there, and the state is pivotal to Biden's campaign strategy.

Perhaps the greatest surprise of the election cycle was in South Carolina, which hasn't elected a Democrat to the Senate since Sen. Fritz Hollings retired 15 years ago. In the Senate elections since 2004, the South Carolina Democratic candidate never cracked 45% of the vote.

But in his race against GOP Sen. Lindsey Graham, Democrat Jaime Harrison raised $57 million between July and September, the largest single-quarter total by any candidate in US Senate history, and lost.

Texas Sen. John Cornyn defeated MJ Hegar, a former Air Force helicopter pilot, despite being outraised by $6.7 million in the third fundraising quarter. And Senate Leadership Fund, the McConnell-aligned super PAC, spent over $16 million on ads in Kansas, a state that hasn't elected a Democratic senator in nearly 90 years, amid anemic fundraising by GOP Rep. Roger Marshall. Still, Marshall beat Democratic candidate Barbara Bollier.

If Democrats do capture the Senate, it will be because of women. A double-digit gender gap is clear in a number of Senate races, according to a series of New York Times/Siena College polls over the past two months. In Arizona, for example, Kelly led McSally overall, 50% to 43%. He was down several points among men but overcame it with a substantial 57% to 38% advantage among women.

Stephanie Schriock, president of EMILY's List, told CNN that Republican efforts to attack the Affordable Care Act, block legislation addressing the gender pay gap and their anti-abortion views have made the GOP unpopular with women. Schriock said that Trump's behavior and "the chaos that he produces constantly" also don't appeal to women. "(It) is just not anything women voters are interested in right now," she added. — Agencies