Triumphant Democrats are expected to regain control of the US House of Representatives after storming multiple Republican districts around the country, handing them the legal power to investigate President Donald Trump and block legislation.

By 11pm local time, Democrats had already seized 19 Republican-held seats in the lower house and were leading in six others, according to The New York Times.

A Democrat-controlled House will be a massive roadblock for President Trump, gaining control of oversight committees with the ability to subpoena and investigate a president who up until this point has controlled both chambers of Congress.

But Democrats must face bruising defeats in the Senate, where they lost seats and the Republicans maintained a majority, leading pundits to pour cold water on the notion of a “big blue wave” in response to the Trump administration.

The election was widely considered a referendum on the controversial presidency of the President, with a record number of Americans turning out to vote and many new women candidates standing for office.

If Democrats regain control of the House, they will be able to launch an investigation into the Trump administration. Photo: Getty

Democrats needed to win 23 seats in the House of Representatives and two seats in the Senate in order to regain control from Republicans in both chambers.

Democrat senators needed to hold on to their seats in addition to capturing another two Republican seats, but suffered bruising defeats. In one of the most-watched races in the campaign, star Democrat candidate Beto O’Rourke narrowly lost to Texan Senator Ted Cruz.

Tremendous success tonight. Thank you to all!

— Donald J. Trump (@realDonaldTrump) November 7, 2018

Professor Simon Jackson, CEO of the University of Sydney’s United States Studies Centre, said he had never seen such fervour surrounding a midterm election.

“I’ve never in my entire adult life seen anything like this,” Mr Jackson told The New Daily in New York.

“I was in the United States in 1994 when [Republican politician] Newt Gingrich took the House away from the Democrats and really set the tone for the rest of the Clinton presidency.

“This is nothing like that. It’s in another order of magnitude again. This is on a whole other level.”

It gives the Democrats the possibility of finding a way to put a brake on Donald Trump and perhaps even more than that, to investigate Donald Trump and to pick up where Robert Mueller’s Russia investigation may leave off.”

The outcome of the election is being described as a “rainbow wave” with women – many veterans, Muslim or openly gay – being elected to office for the first time.

Results: In VA-10, Jennifer Wexton (D) has ousted Rep. Barbara Comstock (R), and in FL-27, Donna Shalala (D) has defeated Maria Elvira Salazar (R). #ElectionNight pic.twitter.com/YnvMKjxi2t

— Democracy Now! (@democracynow) November 7, 2018

A Native American openly-lesbian Democrat wins in Kansas. Interesting things are happening. https://t.co/Qt15a8dMG5

— Matthew Knott (@KnottMatthew) November 7, 2018

https://twitter.com/KhaledBeydoun/status/1059990042960117761

Two-thirds of voters said their midterm election vote was about President Trump, according to a CNN exit poll.

The fervour in this year’s midterm elections has been unprecedented, with a record number of Americans casting their ballots early and women running for office in what is being described as a “pink wave”.

In the week before the election, President Trump took a scorched-earth approach to campaigning and decided to focus on illegal immigration instead of the health of the US economy and low unemployment levels.

Democrats faced emotional losses on the state level. In Florida and Georgia, African-American candidates Stacey Abrams and Andrew Gillum both ran marquee campaigns that drew national media attention.

Gillum had hoped to be the first African-American governor of Florida and Abrams the first female African-American governor in US history, but both were expected to lose to Republicans.

Heartbreaking to see @AndrewGillum concede. But as he said in his outstanding speech, “In the long run, good always wins over evil”. A truly good and decent man that showed such integrity and character in defeat. In time we will still #BringItHome.

— Valerie Jarrett (@ValerieJarrett) November 7, 2018

Yes there were disappointments tonight. @BetoORourke @staceyabrams @AndrewGillum I don’t think its the last we’ll see of them. But people! We took the House back. We have oversight. Subpoena power. I can breathe a bit. First time in 2 years.

— Patrick Fischler (@PFischler) November 7, 2018

While pollsters misjudged several key races, the midterm campaign drew a record-breaking number of people to the polls, showing the unusually emotional and high-stakes nature of the election.

In Texas, one of the most-watched races in the campaign, political strategists believed as many as eight million people would vote.

To put that into perspective, in the 2016 presidential election – a race which held an extraordinarily higher weight – that figure was nine million.