The US Democrats have taken control of the House of Representatives in the mid-term elections, dealing a blow to President Donald Trump. They rode a wave of dissatisfaction with Trump to win the lower chamber of Congress for the first time in eight years.

Tuesday's vote was seen as a referendum on a polarising president, even though he is not up for re-election till 2020, reported BBC.

The election confirms a historical trend for the party that is not in the White House to make gains in the mid-terms.

Democrats converted the energy of the liberal anti-Trump resistance into solid electoral gains in the first nationwide vote since the president swept to power two years ago.

In midterm elections two years after he won the White House, Trump and his fellow Republicans expanded their majority in the US Senate following a divisive campaign marked by fierce clashes over race, immigration and other cultural issues, reported Reuters.

But with his party losing its majority in the House, the results represented a bitter setback for Trump after a campaign that became a referendum on his leadership.

With some races still undecided, Democrats appeared headed to a gain of more than 30 seats, well beyond the 23 they needed to claim their first majority in the 435-member House in eight years.

The newly empowered House Democrats will have the ability to investigate Trump’s tax returns, possible business conflicts of interest and allegations involving his 2016 campaign’s links to Russia.

They also could force Trump to scale back his legislative ambitions, possibly dooming his promises to fund a border wall with Mexico, pass a second major tax-cut package or carry out his hardline policies on trade.

A simple House majority would be enough to impeach Trump if evidence surfaces that he obstructed justice or that his 2016 campaign colluded with Russia. But Congress could not remove him from office without a conviction by a two-thirds majority in the Republican-controlled Senate.

House Democrats could be banking on launching an investigation using the results of US Special Counsel Robert Mueller’s already 18-month-old probe of allegations of Russian interference on Trump’s behalf in the 2016 presidential election. Moscow denies meddling and Trump denies any collusion, said the Reuters report.

“Thanks to you, tomorrow will be a new day in America,” Democratic House leader Nancy Pelosi told cheering Democrats at a Washington victory party, saying House Democrats would be a check on Trump.

“We will have a responsibility to find our common ground where we can, stand our ground where we can’t,” Pelosi said.

The BBC's US partner network CBS projects the Democrats will win the 23 seats they need to take over the lower chamber of Congress. Americans voted for all 435 seats in the House.

House Democratic leader Nancy Pelosi - who is set to become Speaker, a position she held from 2007 to 2011 - told cheering supporters in Washington: "Thanks to you, tomorrow will be a new day in America."

Despite his party losing the House, Trump wrote on Twitter, “Tremendous success tonight.”

President Trump focused on the Senate, and praised himself by quoting a commentator.

 “There’s only been 5 times in the last 105 years that an incumbent President has won seats in the Senate in the off year election. Mr. Trump has magic about him. This guy has magic coming out of his ears. He is an astonishing vote getter & campaigner. The Republicans are.........," said the tweet.

Female candidates performed particularly well in an election cycle that had been billed as the Year of the Woman.

Two 29-year-old Democrats, Alexandria Ocasio-Cortez and Abby Finkenauer - are due to be the youngest women ever to win House seats.

Ilhan OImar and Rashida Tlaib are the first Muslim women and Sharice Davids and Debra Haaland the first Native American women to be elected to Congress. All are Democrats.

Despite the tight poll race, most Democratic candidates stayed away from harsh criticism of Trump during the campaign’s final stretch, focusing instead on bread-and-butter issues like maintaining insurance protections for people with pre-existing medical conditions and safeguarding the Social Security retirement and Medicare healthcare programs for senior citizens.

n the last two decades there have only three election cycles where one party picked up 24 or more seats. Tuesday’s gains were the biggest since 2010, when a wave of conservative anger against Democratic President Barack Obama gave Republicans a massive 64-seat pickup.

Every seat in the House, 35 seats in the 100-member Senate and 36 of the 50 state governorships were up for grabs.