And keeping hold of the Senate is especially important for Trump since it will give the White House the chance to press on with one of his major legacy-building initiatives, restocking the federal judiciary with conservatives.
Republican Whip Steve Scalise said the president's rallies were building momentum and with the economy a selling point, he predicted his party would retain a slim majority.
But the GOP solidified their Senate majority after an acerbic midterm election that enshrined America's deep political divides and shaped a highly contentious battleground for the stirring 2020 presidential race.
And Rep. Adam Schiff, slated to become chairman of the House Intelligence Committee, has vowed to probe alleged Trump campaign-Russia collusion.
"We will have a responsibility to find our common ground where we can, stand our ground where we can't", Pelosi said.
Trump - a 72-year-old former reality TV star and businessman-turned-politician - had hardened his rhetoric down the stretch on issues that appealed to his conservative core supporters, issuing warnings about a caravan of Latin American migrants headed to the border with Mexico and condemnations of liberal American "mobs".More news: Red Dead Redemption 2 Mexico Can Be Explored Through A Glitch
Historically, the party in power loses several seats during the first midterm election of a new president, particularly if his national job approval ratings are low.
With media outlets projecting the Dems are going to retake the House of Representatives, the party is apparently not waiting for the gavel to start making moves against the president.
Every seat in the House, 35 seats in the 100-member Senate and 36 of the 50 state governorships were up for grabs.
But the election also likely means Democrats will have to bridge the demands of a party that has grown to embrace progressives, like Alexandria Ocasio-Cortez, who won in a safely Democratic district in NY, while electing moderates like Conor Lamb in Pennsylvania, who won a special election earlier this year and won Tuesday in a reconfigured district.
Breaking the Republican monopoly on power, Democrats had already picked up over two dozen seats in the House - more than the 23 needed to take control of the House for the first time in eight years.
In the Senate, where Republicans were heavily favored to keep control heading into Tuesday's voting, Republican Mike Braun captured incumbent Joe Donnelly's seat In IN and Republican Kevin Cramer beat incumbent Democratic Senator Heidi Heitkamp In North Dakota.
Democrats landed on a plan to allow each vulnerable Democrat to run an independent campaign without a unified platform.More news: Scientists Believe Mysterious, Oddly Shaped Space Object Could Be 'Alien Probe'
EL PASO, TEXAS - NOVEMBER 06: U.S. Senate candidate Rep. Beto O'Rourke (D-TX) concedes the race while addressing a "thank you" party on Election Day at Southwest University Park November 06, 2018 in El Paso, Texas. Both Republicans Rick Scott in the Senate race and Ron DeSantis in the governor's race hold leads in Florida.
Whether or not the night constitutes a "blue wave" for Democrats is unclear given the mixed results overall and the typical losses for the president's party, but the split Congress will make life more hard for the president. Along with Sherrod Brown, a pro-labor lawmaker re-elected in OH, the four are considered potential 2020 Democratic presidential hopefuls.
Once in control of the three branches of government, Democrats are expected to take on issues like access to abortion, health care and affordable housing. Democrat state legislator Laura Kelly will be that state's next governor.
His visits included overt reminders to his base supporters that they weren't just voting for any Republican on the ballot - they were voting for senators promising to back his priorities. House Majority Whip Steve Scalise may also be interested in climbing the GOP leadership ranks though he has said he would not challenge McCarthy in a race for speaker.
Republicans and Democrats will split control of Congress next year.
In turn, Trump began trying out defensive arguments ahead of Election Day, noting that midterm losses are typical for the party in the White House, pointing out a high number of GOP retirements and stressing that he had kept his focus on the Senate.More news: Ariana Grande Slips During 'thank u, next' Performance On Ellen