Thomson Reuters
Senate Majority Leader Mitch McConnell speaks to reporters in the U.S. Capitol in Washington
Sen. Pat Toomey of Pennsylvania was the deciding race, as he defeated Democratic challenger Katie McGinty.
Republicans had feared that they would lose control of Congress with Donald Trump leading their ticket. Trump was a controversial and unconventional candidate throughout the primaries and general election and shocked establishment Republicans when he won the party's nomination.
Establishment Republicans had worried that Trump could hurt down-ballot candidates in the House and Senate, and Senate Republicans were forced to choose between distancing themselves from Trump and embracing the party's nominee in an effort not to burn bridges.
Senate Majority Leader Mitch McConnell spoke up in Trump's favor last week.
"We need a new president, Donald Trump, to be the most powerful Republican in America," McConnell said at a rally in his home state of Kentucky.
He had previously been reluctant to vocally support Trump as some senators up for reelection distanced themselves from him.