Republicans have picked up a crucial win in the race for the Senate majority.
Early in the evening, West Virginia Republican Jim Justice won the Senate seat opened by senator Joe Manchin’s retirement.
Republicans also quickly dispatched a late challenge by Democrats in Florida as senator Rick Scott sailed to re-election after pouring millions of dollars of his own wealth into the campaign.
In Ohio and the Democratic “blue-wall” states of Pennsylvania, Michigan and Wisconsin, Democrats fought to salvage what is left of their slim hold on the Senate.
The Ohio race between senator Sherrod Brown and wealthy Trump-backed Bernie Moreno is the most expensive of the cycle, at some 400 million dollars.
And in Nebraska, attention turned suddenly to a state that vaulted to importance with competitive races in both the House and the Senate, where independent newcomer Dan Osborn challenged incumbent Republican senator Deb Fischer.
With control of Congress at stake, the ever-tight contests for the House and Senate will determine which party holds the majority and the power to boost or block a president’s agenda.
In the end, just a handful of seats, or as little as one, could tip the balance in either chamber. With a 50-50 Senate, the party in the White House determines the majority, since the vice president is a tie-breaker.
Already several states will send history-makers to the Senate.
Voters elected two black women to the Senate, Democrat Lisa Blunt Rochester of Delaware and Democrat Angela Alsobrooks of Maryland, in a historic first.
Ms Blunt Rochester won the open seat in her state while Ms Alsobrooks defeated Maryland’s popular former governor, Larry Hogan. Just three black women have served in the Senate, and never before have two served at the same time.
And in New Jersey, Andy Kim became the first Korean American elected to the Senate, defeating Republican businessman Curtis Bashaw. The seat opened when Bob Menendez resigned this year after his federal conviction on bribery charges.
Elsewhere, House candidate Sarah McBride, a Democratic state politician from Delaware who is close to the Biden family, won her race, becoming the first openly transgender person elected to Congress.
Top House races are focused in New York and California, where Democrats are trying to claw back some of the 10 or so seats where Republicans have made surprising gains in recent years.
Other House races are scattered around the country in a sign of how narrow the field has become. Only a couple of dozen seats are being seriously challenged.
Vote counting in some races could extend well past Tuesday.
“We’re in striking distance in terms of taking back the House,” House Democratic leader Hakeem Jeffries, who is in line to make history as the first black speaker if his party wins control, told The Associated Press during a recent campaign swing through Southern California.
But House speaker Mike Johnson, drawing closer to Mr Trump, predicts Republicans will keep “and grow” the majority. He took over after Kevin McCarthy was booted from the speaker’s office.
One of the most-watched Senate races, in Montana, may be among the last to be decided. Democrat Jon Tester, a popular three-term senator and “dirt farmer” is in the fight of his political career against Trump-backed Tim Sheehy, a wealthy former Navy Seal, who made derogatory comments about Native Americans, a key constituency in the Western state.
