After a hard-fought contest largely centered on President Donald Trump’s performance and policies, the Democratic Party will wrest control of the House of Representatives from the Republicans, NBC News projected.
But the GOP gained ground in the Senate and preserved key governorships, beating back a "blue wave" that never fully materialized.
Still, the new Democratic House majority ends the Republican Party's dominance in Washington for the final two years of Trump's first term with major questions looming about health care, immigration and government spending. The president's party will maintain control of the executive and judicial branches of U.S. government, in addition to the Senate, but Democrats suddenly have a foothold that gives them subpoena power to probe deep into Trump's personal and professional missteps — and his long-withheld tax returns.
Though the Republican Party retained control of the Senate, a win for the Democrats in the House would end the GOP monopoly on power in Washington and open a new era of divided government.
"Tomorrow will be a new day in America," Democratic Leader Nancy Pelosi said at a victory party in Washington.
The campaign unfolded against a backdrop of ugly rhetoric and angry debates on immigration, health care and the role of Congress in overseeing the president.
Midterm elections are typically difficult for the party in power, but the GOP's hold on power was further weakened by an unusually large number of retirements as well as infighting between conservatives and centrists over their allegiance to Trump.
The Democrats, in turn, benefited from extraordinary voter enthusiasm, robust fundraising and unusually fresh candidates. More women than ever were running, along with veterans and minorities, many of them motivated by revulsion over Trump.
In the suburbs outside the nation's capital, Virginia Rep. Barbara Comstock — among the most endangered GOP incumbents, branded Barbara "Trumpstock" by Democrats — lost to Jennifer Wexton, a prosecutor and state legislator.
And outside Richmond, Virginia, one-time tea party favorite Rep. Dave Brat lost to Democrat Abigail Spanberger, a former CIA operative motivated to run for office after the GOP vote to gut the Affordable Care Act. Like other Democrats across the country, Spanberger emphasized protecting people with pre-existing conditions from being denied coverage or charged more by insurers, NBC News reported.
Pennsylvania was particularly daunting for Republicans after court-imposed redistricting and a rash of retirements put several seats in play. Democratic favorite Conor Lamb, who stunned Washington by winning a special election in the state, beat Republican Rep. Keith Rothfus in a new district. At least three other red districts flipped to blue.
In Kansas, Democrat Sharice Davids beat a GOP incumbent to become one of two Native American women, with Deb Haaland of New Mexico, elected to the House. Davids is also openly gay.
Democrats welcomed other firsts, including two Muslim-American women, Rhasida Tlaib of Michigan and Minnesota's Ilhan Oman, who is also the first Somali-American elected to Congress. The Republican side of the aisle elected mostly white men.
But in Kentucky, one of the top Democratic recruits, retired Marine fighter pilot Amy McGrath, lost her bid to oust to three-term Rep. Andy Barr in the Lexington-area district.
While NBC projected that Sen. Ted Cruz, R-Texas, would retain his Senate seat, fighting off Democratic challenger Rep. Beto O'Rourke, Democrats on the House side were projected to defeat other high-profile Texas incumbents.
Eleven-term GOP Rep. Pete Sessions, who has served as chairman of the powerful Rules Committee since 2013, was projected to lose his Dallas-area seat to Democrat Colin Allred, a former NFL player and civil rights attorney. And Rep. John Culberson, who has served in the House since 2001, was on track to be defeated by Democrat Lizzie Fletcher in a district that Clinton carried by 1 percentage point two years ago.
Kendra Horn was on her way to victory in Oklahoma's 5th Congressional District, which covers the Oklahoma City area and hadn't been held by a Democrat since 1975.
And on Staten Island, Democrat Max Rose was projected to pull off a surprise upset of incumbent Rep. Dan Donovan, R-N.Y., on a night in which Democratic candidates north of the New York metropolitan area won two toss-up races against the GOP incumbents.
But Republicans appeared to hold on in some closely-fought contests, such as Virginia's 5th Congressional District: the seat, which had been held by GOP Rep. Tom Garrett, was projected to go to Republican Denver Riggleman over Democrat Leslie Cockburn.
In Kentucky's 6th Congressional District, Rep. Andy Barr was projected to hold off a stiff challenge by Democrat Amy McGrath. Republican Bryan Steil will hold onto the seat in Wisconsin held by Speaker Paul Ryan who is set to retire at the end of the year.
And two Republican incumbents who were indicted this year — Duncan Hunter in California and Chris Collins in New York — both won their races.
Across the country, voter turnout records seemed poised to fall, as the fight over control of Congress reached the final round of what was widely viewed as a referendum on President Trump and his first two years in office.
According to NBC News exit polls, two out of every three voters Tuesday said Trump was a factor in their House vote, with 26 percent saying they cast their vote to express support for the president and 38 percent saying their vote was intended to oppose the president.
In trying to stem Republican losses, Trump made only passing reference to his $1.5 trillion tax cut — the GOP Congress' signature achievement — and instead barnstormed through mostly white regions of the country, interjecting dark and foreboding warnings. He predicted an "invasion" from the migrant caravan making its way toward the U.S. and decried the "radical" agenda of speaker-in-waiting Pelosi.
On Tuesday night, Trump called to congratulate Pelosi and acknowledged her plea for bipartisanship, the leader's spokesman said.
With control of the House, Democrats will chair powerful committees and have subpoena power to seek Trump's tax returns and more aggressively investigate Russian interference in the 2016 election and whether there was any collusion by the president's campaign.
The Associated Press contributed to this report.