Elizabeth Warren, the Massachusetts senator, won her re-election bid on Nov. 6.
Warren, a Democrat, was expected to defeat Republican challenger Geoff Diehl.
The Associated Press, Politico, and other news outlets have called the race for her.
The win effectively sets her up for a presidential run. “Thank you, Massachusetts! Six years ago, I promised to go to Washington to fight for you every single day. Tonight, let’s send the powerful interests a message: We’re just getting started,” she wrote on Twitter.
Diehl had attacked Warren for her desire to run for president.
“[S]he doesn’t care about your house,” Diehl said, WBUR reported. “She cares about the White House.”
White House press secretary Sarah Sanders, meanwhile, said that President Donald Trump and First Lady Melania Trump are watching the election results with “friends and family” at the White House. She said the president’s rally schedule triggered “an extraordinary ground game geared toward defying midterm history and protecting the GOP’s majorities.”