But Fox News' Decision Desk projection that Democrats will now control of the House gives hope to liberals who want to continue the Russian Federation investigation, and even introduce articles of impeachment against the president.
Blackburn, a conservative who is also an ardent Trump backer, defeated former Tennessee Gov. Phil Bredesen, 74.
Democrats were elected to more than 34 seats and now occupy a majority of the state Senate's 63 seats. We are going to see a Democratic majority (in the House) that is going to do everything it can to hold the Trump administration's feet to the fire and use subpoena power to do so. The GOP's grip on high-profile governorships in Florida, Georgia and Wisconsin were at risk as well.
At a polling station in Arlington, Virginia, head election officer William Harkins said "it's a very good turnout".
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.
As the first national election since Mr Trump's presidential upset in 2016, the midterms gave Democrats an opportunity to capitalise on his low 40pc approval rating, a restive national mood and frustration with one-party leadership in Washington under the GOP.
Sen. Joe Manchin was the lone Democrat to back Kavanaugh, and his yes vote is believed to have put him over the top in a hotly contested race.
Some GOP incumbents in Clinton districts have prevailed, including Rep.
The election is the culmination of two years of Democratic activism beginning virtually the day after Trump won the 2016 election and officially kicking off with Women's Marches across the country on the day after his inauguration.
Overall, Democrats were defending seats in 10 states that Trump took in 2016, including five he won by at least a huge 19 percentage points.
He bet big on a xenophobic closing message, warning of an immigrant "invasion" that promised to spread violent crime and drugs across the nation.
Knowing that House Democrats will not approve funding for a wall along the United States border, for example, will not keep Trump from continuing to make it an issue. Liberals hope that a Republican defeat in the midterm could halt this trend. Democratic Senator Sherrod Brown was projected to hold his seat in Ohio.
On Tuesday, a number of U.S. House races were close.
As Election Day unfolded, Democrats were increasingly confident, predicting they would pick up at least the 23 seats needed for a House majority on the strength of voter enthusiasm, robust fundraising and unusually fresh candidates.
All of it leaves Trump a more dominant force in the party than he was even two years ago.
Sanders' interview came before Democrats were projected to win the House, and at that time pointed out that the races were still early.
The White House for days has been stressing the historical headwinds it faced: In the last three decades, 2002 was the only midterm election when the party holding the White House gained Senate seats. In places like Colorado, New Jersey, Kansas, Pennsylvania, Texas and New York, Democrats are poised for victory. Democratic Senate incumbents were up for re-election, for example, in North Dakota, Indiana, and Missouri - states Trump carried by nearly 25 percentage points on average two years ago.
But Andrew Gillum lost to Republican Ron DeSantis in his quest to become the first African-American governor of the key swing state of Florida.
The Democratic victory also proves that Republicans are far from invincible under Mr. Trump, a natural showman beloved by the GOP's grassroots but with more limited appeal in the cities and suburbs.