Republicans Maintain Control of US Senate

— -- In a turn of events that reflects the election's unpredictable results up and down the ticket, Republicans will hold onto control of the U.S. Senate despite predictions that they would at least narrowly lose their majority in the upper chamber of Congress.

With ABC News' projection of the Pennsylvania Senate race going to incumbent Republican Sen. Pat Toomey, the party achieved at least a 51-seat majority, removing any chance Democrats had to capture enough seats to split the Senate 50-50, a scenario that many political observers had expected.

Around 3 a.m., ABC News projected incumbent Republican Sen. Roy Blunt the winner of the Missouri Senate race, bringing the Republicans' total to 52.

The New Hampshire Senate race was still yet to be called as the wee hours of the morning approached.

Republican incumbents did lose in Illinois, where Sen. Mark Kirk was considered the most endangered of his colleagues, but Sen. Ron Johnson of Wisconsin, who was considered nearly as vulnerable as Kirk, survived the night.

Even as polls closed on election night, the fate of the Senate was unclear. Republicans went into the night holding a 54-seat majority but having a much tougher job than Democrats, who had to defend 10 incumbents, most of whom were in solid blue territory, compared to 24 GOP incumbents running for reelection.

But as GOP presidential nominee Donald Trump racked up victories in key states like Florida and Ohio, Republican Senate candidates also performed well, maintaining the party's hold on seats in Ohio, Florida, Indiana and North Carolina earlier in the night and Pennsylvania, which was called after midnight on the East Coast.

The results in the Senate were just as unforeseen as they were decisive.

At least two expert electoral prognosticators, nonpartisans Charlie Cook and Larry Sabato, predicted a Hillary Clinton presidential victory and the Senate split 50-50, with a Vice President Tim Kaine casting tiebreaking votes.

“We’re forecasting Democrats to win control of the Senate, but only by the slimmest of margins,” Sabato wrote.

But as the clock ticked toward the closing of polls, both the Democratic and Republican Senate campaign committees expressed confidence that they’d taste victory by the end of the night.

“Our campaigns and allies didn’t just rely on Trump bringing down the party. We made strong cases to disqualify our opponents on their own records -- defunding Planned Parenthood, supporting outsourcers, opposing student loan relief and much more. The result was remarkable stability in our races,” Sadie Weiner, the communications director for the Democratic Senatorial Campaign Committee, said in an email.

Andrea Bozek, communications director for the National Republican Senatorial Committee, said, “Democrats had a fatal and fundamental flaw in their plan to take control of the Senate: their efforts did not rely on having better candidates running better races than their opponents. While Republicans have worked nonstop since day one of this campaign to build nimble, data-driven campaigns, Democrats have relied on political gravity from the presidential race to carry them across the finish line.”