Democrats were on course to flip at least 26 seats from Republican hands, with strong performances among suburban white women who had narrowly turned to Trump two years ago and in key battleground states such as Pennsylvania.
"It's like being the rescue team at an 88-car pileup: Who knows where to begin?" asked Representative Jamie Raskin, Democrat of Maryland.
"I think we are excited, but we also feel there is a major responsibility to deliver on the promises we made", Libby said.
Trump said in a wide-ranging news conference Wednesday that he doesn't want to release his taxes because they are under a "continuous audit".
Those measures, they believe, will be broadly popular.
For the past two years, White House lawyers and the Trump Organisation have repeatedly rebuffed Democratic efforts to get even the most basic financial information on Trump's businesses.
Democrats have called for investigations of Cabinet officials' alleged misuse of taxpayer funds, Trump's immigration policies that have separated hundreds of migrant children from their parents at the U.S. That could lead to gridlock.
Some political pundits say that the midterm could also decide whether Mr Trump will be a one or two-term president. "There's an expectation that we're a check and a balance so that means a stalemate".
A record number of women were elected to the House on Tuesday, almost two years after women spilled out into the streets of Washington and in cities across the country in defiance of the inauguration of U.S. President Donald Trump.
The result confirms a historical trend for the party that is not in the White House to make gains in the mid-terms. It was on par with other recent midterm "wave" elections which had margins of 7.1 for the Republicans in 1994; 8.0 for the Democrats in 2006; 7.2 in 2010 and 5.7 in 2014 for the Republicans.
"This is the year of the woman, and the fact that women were willing to put themselves on the line is important, whether they've been Republicans or Democrats", said former Health and Human Services Secretary Donna Shalala, a first-time candidate who defeated Republican Maria Elvira Salazar in south Florida.
But they do have a lot to celebrate. Democrats relied more upon women, people of colour, young people and college graduates.
A split Congress will empower both parties in different ways.
In Texas, Democrat Colin Allred, a former National Football League player and civil rights lawyer, defeated the incumbent Republican, Pete Sessions. In Illinois, Lauren Underwood beat Representative Randy Hultgren, a Republican who won by 19 points in 2016.
With three more committee members running for other offices, come January, half of the 24 Republicans who wrote the 2017 Tax Cuts and Jobs Act will no longer be in Congress.
"This polarisation of United States society has not disappeared of course, and what is striking in that is how we talk about who will be the next Democratic candidate for 2020". Many are from the party's progressive wing.
Ayanna Pressley was elected as Massachusetts' first black congresswoman. Democrats also reclaimed a handful of blue-collar districts carried by both former President Barack Obama and Trump.
"We took a thumping in the rural areas and I understand that", Heitkamp said.
Aides said the president was delighted at the projected victories by Republican Senate candidates he had campaigned for, such as Marsha Blackburn of Tennessee, Rick Scott of Florida, Mike Braun of IN and Josh Hawley of Missouri, as well as Republican Brian Kemp's victory IN the Georgia governor's race.
Trump's show of support for Pelosi is not entirely out of character.