The Republicans were declared the majority party in the U.S. House of Representatives Wednesday, completing a clean sweep of Congress and the White House in last week's elections and handing incoming president Donald Trump vast legislative power.

After more than a week of vote counting, CNN and NBC projected that Trump's party had reached the 218 seats needed to retain their majority in the 435-seat lower chamber, having already seized the Senate from the Democrats.

"It is a beautiful morning in Washington. It is a new day in America," said House Speaker Mike Johnson, who held a press conference to celebrate victory Tuesday before the result was official.

"The sun is shining, and that's a reflection about how we all feel. This is a very, very important moment for the country and we do not take it lightly."

Trump triumphed in every swing state in the November 5 presidential election and also looked to have won the national popular vote, with preliminary figures showing him ahead of Democratic Party challenger Kamala Harris by 3.2 million votes.

Having control of both chambers of Congress will clear the way for him to confirm his nominations for key administration positions and will also allow him to push through his radical agenda of mass deportations, tax cuts and slashing regulations.

Conservative tilt

"We need positions filled IMMEDIATELY!" Trump wrote on the X social media network on Sunday, referring to the need for the Republican-majority Senate to quickly approve his cabinet picks.

He is also seen by analysts as facing fewer judicial constraints than previous presidents, with his nominations to the Supreme Court during his first term, from 2017-2021, having given the high court a heavily conservative tilt.

The Republicans' sweep of the presidency and Congress is not unusual, with Trump in his first term and Democratic predecessors Joe Biden and Barack Obama also benefiting from majorities at the start of their presidencies.

But the loss of the House extinguishes any remaining hope among Democrats that they might be able to stand in the way of Trump's agenda for now.

On a huge day for governance in Washington, Senate Republicans picked a traditionalist, John Thune, as the chamber's new leader -- rejecting Trump favorite Rick Scott in a secret ballot.

The Senate -- the upper chamber of Congress -- jealously guards its independence and institutional authority, and its leadership election was seen as a clue into how much leeway members intend to give Trump.

'Work starts today'

The incoming Republican has promised more tax cuts, a gutting of environmental and other regulations, as well as a crackdown on crime, immigration and his political opponents.

He has begun to assemble his second administration by naming campaign manager Susie Wiles to serve as his White House chief of staff, as well as appointing loyalists such as Senator Marco Rubio and Congressman Mike Waltz to his national security team.

"This Republican team is united behind President Trump's agenda, and our work starts today," Thune, who represents South Dakota, said in a brief statement -- revealing later that he had spoken on the telephone with Trump.

Trump is expected to further test lawmakers early in his presidency with pardons for rioters convicted in the 2021 storming of the Capitol, sweeping import tariffs and vast tax cuts expected to pile on debt.

The top priority for both parties in both chambers is funding the government to keep federal agencies open after December 20, with Republicans mulling a stop-gap measure that would keep the lights on into March.

The entire House of Representatives -- Democrats as well as Republicans -- gets to vote on the speaker, meaning Mike Johnson has to wait until the new Congress convenes in January to find out if he can hang on to the gavel.