The focus has turned to Nevada, where Senator Catherine Cortez Masto, a Democrat and the first Latina elected to the Senate, pulled ahead of her Republican challenger, Adam Laxalt, a former state attorney general.
The state is expected to release more results later on Saturday, and a race call could determine whether Democrats will hold on to power in the chamber, or if the Dec. 6 runoff in Georgia between Senator Raphael Warnock, a Democrat, and his Trump-backed challenger, Herschel Walker, will provide the decisive moment.
A 50-50 tie in the Senate would be enough for Democrats to maintain control of the chamber, where Vice President Kamala Harris holds the tiebreaking vote.
Republicans still appear to have an edge in claiming control of the House, with several races still outstanding. But on Saturday, Democrats captured the Washington State seat held by Representative Jaime Herrera Beutler, one of the 10 Republicans who voted to impeach former President Donald J. Trump. Ms. Herrera Beutler was ousted in her primary.
Marie Gluesenkamp Perez, a Democrat, defeated Joe Kent, an election denier, to pick up the seat for her party.
Here’s what else to know:
The victory by Senator Mark Kelly of Arizona on Friday was crucial to positioning Ms. Cortez Masto’s race as the contest that may determine control of the Senate. Mr. Kelly defeated Blake Masters, a venture capitalist endorsed by Mr. Trump.
The Republican candidate for Arizona governor, Kari Lake, continued to trail her Democratic opponent, Katie Hobbs, in what has been a tight race. More results are expected from Maricopa County on Saturday night.
In Arizona’s secretary of state race, Adrian Fontes, a Democrat, defeated Mark Finchem. Mr. Finchem, one of the nation’s leading election deniers, had begun casting unfounded doubts on this year’s races as it appeared that he might lose.
Republicans took over the governor’s office in Nevada, with the Clark County sheriff, Joseph Lombardo, ousting Gov. Steve Sisolak.