Midterm election a 'big day' for Republicans – Trump

US President Donald Trump on Wednesday hailed a "big day" for Republicans after his party lost the House of Representatives in the US midterm elections but increased their majority in the Senate.

"It was a big day yesterday, an incredible day," Trump told a news conference at the White House.

"And last night ... the Republican Party defied history to expand our Senate majority while significantly beating expectations in the House."

Trump expressed hope that Republicans and Democrats can "work together" after midterm elections that left the lower house of Congress under Democratic control.

TRT World's Jon Brain reports from Washington, DC.

Trump hails Pelosi

Trump also praised Nancy Pelosi, the Democratic leader and likely next speaker of the House of Representatives, saying he gave her "a great deal of credit" and extending an olive branch of sorts.

"Hopefully we can all work together next year to continue delivering for the American people. Including on economic growth, infrastructure, trade, lowering the cost of prescription drugs," he said.

Trump also envisaged Republicans and Democrats working together on infrastructure and healthcare after US voters delivered a split verdict in hard-fought midterm elections.

"Maybe we will make a deal, maybe we won't. That is possible. But we have a lot of things in common on infrastructure. We want to do something on healthcare, they want to do something on healthcare. There are a lot of great things that we can do together," he said.

Deeper political polarisation

The divided power in Congress combined with Trump's expansive view of executive power could herald even deeper political polarisation and legislative gridlock in Washington.

The Democrats will now head House committees that can investigate the president's tax returns, possible business conflicts of interest and any links between his 2016 election campaign and Russia.

There may be some room, however, for Trump and Democrats to work together on issues with bipartisan support such as a package to improve infrastructure or protections against prescription drug price increases.

"It really could be a beautiful bipartisan situation," Trump said.

But Trump doubted there would be much common ground if Democrats press investigations.

He said if House Democrats flood him with subpoenas, "we're going to do the same thing" and government will come to a halt.

Russian probe a 'hoax'

Warning Democrats on potential investigations, he said, "they can play that game but we can play it better."

"I could fire everybody right now, but I don't want to stop it because politically I don't like stopping it," Trump said.

"I am not concerned about anything with the Russian investigation, because it is a hoax," the president said. "There's no collusion."

Spars with media over caravan queries

Trump sparred with reporters at his post-election news conference, ordering several to sit down and telling another he's a "rude, terrible" person.

He told yet another reporter he's "not a fan of yours, either."

The president's mood turned sour after reporters pressed him on why he referred to a migrant caravan making its way to the US on foot through Mexico as an "invasion." 

Trump ramped up his anti-immigrant rhetoric against the caravan in the final days of the midterm elections.

Trump was also pressed on why his campaign aired an ad featuring a Mexican immigrant convicted of killing American police officers and linking the man's actions to the caravan.

Several television networks pulled the ad after airing it or declined to air it at all.

Border wall funding

The US president said he hopes he can work with Congress on immigration to fund his border wall, as well as possibly addressing the thousands of young immigrants living in the United States without legal status.

Trump said he wanted to see US lawmakers provide enough money to build his long-promised wall along the southern US border with Mexico. But he said he would not necessarily force a government shutdown over the issue.

"We need the money to build the wall, the whole wall, not pieces of it," Trump told reporters. "We need the wall, many Democrats know we need the wall, and we're just going to have to see what happens."

The Republican president also said he saw potential to work with Democrats over the Deferred Action for Childhood Arrivals (DACA) programme but would have to see how the US. Supreme Court ruled on the issue.

The programme has shielded from deportation immigrants dubbed "Dreamers" and given them work permits, though not a path to citizenship.

Trump's administration on Monday asked the nation's top court to allow it to end the programme.

"I think we could really do something having to do with DACA," Trump told reporters. "We'll see how it works out at the Supreme Court."

Summit with North Korea's Kim

Trump said he expected to meet with North Korea's leader Kim Jong-un some time early next year and that an expected meeting between US Secretary of State Mike Pompeo and officials from the reclusive Asian nation will be rescheduled.

"We're very happy how it's going with North Korea. We think it's going fine. We're in no rush," he said at a press conference. 

"The sanctions are on. ... I'd love to take the sanctions off, but they (North Korea) have to be responsive, too."