Republicans kept control of the U.S. Senate Tuesday night after several key victories in tight races.
Democrats have been projected to win enough seats to take control of the House after eight years of Republican rule.
The GOP Senate victory was magnified because Democrats stood a solid chance of wresting control of the House from Republicans.
Victories in contested House races across Florida, New York, Virginia, Pennsylvania and Minnesota gave them cause for optimism.
While Sanders suggested Trump could blow off Pelosi in the wake of the midterms, she noted that the president is willing to work with whatever party ultimately ends up in power.
In Texas, one of the most closely watched races of the 2018 political season, Republican incumbent and one-time Trump foil Ted Cruz managed to fend off a concerted challenge from the charismatic Beto O'Rourke, whose youthful exuberance and ability to mobilize younger voters made him a national Democratic superstar.
The Senate majority leader is Mitch McConnell of Kentucky.
Blackburn, a conservative who is also an ardent Trump backer, defeated former Tennessee Gov. Phil Bredesen, 74. If he is successful, he would become the first Democrat elected to the Senate in Texas in three decades.
GOP hopes of gaining a seat from New Jersey were dashed when Democrat Sen.
Long lines and malfunctioning machines marred the first hours of voting in some precincts, including in Georgia, where some voters reported waiting up to three hours to vote in a hotly contested gubernatorial election.
Overall, 6 in 10 voters said the country was headed in the wrong direction, but roughly that same number described the national economy as excellent or good.
In the Miami area, former Clinton administration Cabinet member Donna Shalala won an open seat, while GOP Rep. Carlos Curbelo lost his bid for a third term in another district.
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However, video posted to Twitter and broadcast on television showed a man repeatedly swinging an object at two police officers. He was said to have extremist links and had run-ins with local police over drug use and theft, according to media reports .
Also victorious was Republican Mitt Romney, the vanquished 2012 GOP presidential candidate who grabbed the Utah seat being vacated by the retiring GOP Sen.
Democratic Sen. Joe Manchin was re-elected in West Virginia, a state Trump captured by 42 percentage points in his 2016 election triumph.
Trump also took little responsibility for the House, saying his focus was on saving the Senate. It is now made up of 51 Republicans and 49 Democrats.
Republicans now control 29 governorships to 21 for the Democrats.
Americans were voting for all 435 seats in the House of Representatives and 35 of 100 seats in the Senate - the two bodies that make up Congress. Governors are also being chosen in 36 out of 50 states.
Vermont independent Sen. Bernie Sanders and Democrats Elizabeth Warren of Massachusetts, Kirsten Gillibrand of NY and Minnesota's Amy Klobuchar were easily re-elected.
The result upends the balance of power in Washington, where Trump has enjoyed an easy ride from Republican dominance of both houses of Congress since his shock election in 2016.
Almost 40 percent of voters cast their ballots to express opposition to the president, according to AP VoteCast, a national survey of the electorate, while one-in-four said they voted to express support for Trump. The other 29 Republican-held seats are considered toss-ups.
Tuesday's elections tested the strength of a Trump-era political realignment defined by evolving divisions among voters by race, gender, and especially education.
Trump encouraged voters to view the first nationwide election of his presidency as a referendum on his leadership, pointing proudly to the surging economy at recent rallies. Democrats were able to ride opposition to Trump to wins in more Democratic-leaning states like NY and deep-red states like Oklahoma.
In the Senate, where Republicans were heavily favoured 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.