US riots: Senate Republican leader Mitch McConnell says Donald Trump 'fed lies' to Capitol mob

US Senate Republican leader Mitch McConnell opened the Senate today saying the pro-Trump mob that stormed the Capitol was "fed lies" by President Donald Trump and others.

McConnell's remarks are his most severe and public rebuke of the outgoing president. The Republican leader vowed a "safe and successful" inauguration of President-elect Joe Biden tomorrow at the Capitol, which is under extremely tight security.

"The mob was fed lies," McConnell said. "They were provoked by the President and other powerful people, and they tried to use fear and violence to stop a specific proceeding of branch of the federal government."

McConnell said after Biden's inauguration on the Capitol's West Front — what he noted former President George H.W. Bush has called "democracy's front porch" — "We'll move forward."

Senate Majority Leader Mitch McConnell: "[The Capitol rioters] were provoked by the President and other powerful people." Photo / AP

Trump's last full day in office is also senators' first day back since the deadly Capitol siege, an unparalleled time of transition as the Senate presses ahead to his impeachment trial and starts confirmation hearings on Biden's Cabinet.

Three new Democratic senators-elect are set to be sworn into office tomorrow, shortly after Biden's inauguration at the Capitol, which is under extreme security since the bloody pro-Trump riot.

The new senators' arrival will give the Democrats the most slim majority, a 50-50 divided Senate chamber, with the new vice president, Kamala Harris, swearing them in and serving as an eventual tie-breaking vote.

McConnell and Senate Democratic leader Chuck Schumer are set to negotiate a power-sharing agreement for the Senate that was last split so narrowly nearly 20 years ago, according to a person familiar with the planning.

The Senate leaders also must negotiate a power-sharing agreement for the Senate that was last split so narrowly nearly 20 years ago, as they divvy up committee assignments and other resources.

The start of the new session of Congress will force senators to come to terms with the post-Trump era, a transfer of power like almost none other in the nation's history. Senators are returning to a Capitol shattered from the riot, but also a Senate ground to a halt by the lawmakers' own extreme partisanship.

Republican senators, in particular, face a daunting choice of whether to convict Trump of inciting the insurrection, the first impeachment trial of a president no longer in office, in a break with the defeated president who continues to hold great sway over the party but whose future is uncertain.

A view of the National Mall in Washington DC today, ahead of the 59th Presidential Inauguration. Photo / AP

Senators are also being asked to start confirming Biden's Cabinet nominees and consider passage of a sweeping new US$1.9 trillion (NZ$2.6t) Covid-19 relief bill.

In opening remarks at his confirmation hearing, Biden's nominee for secretary of the Department of Homeland Security, Alejandro Mayorkas, vowed to get to the bottom of the "horrifying" attack on the Capitol.

Mayorkas told the Senate Homeland Security Committee that if confirmed he would do everything possible to ensure "the desecration of the building that stands as one of the three pillars of our democracy, and the terror felt by you, your colleagues, staff, and everyone present, will not happen again".

Biden wants the Senate to toggle between confirming his nominees, considering Covid relief and holding Trump accountable with the impeachment trial, a tall order for an institution that typically runs more slowly and with bitter confrontations.

The House impeached Trump last week on a sole charge, incitement of insurrection, making him the only president to be twice impeached. He had been impeached in 2019 over relations with Ukraine and was acquitted in 2020 by the Senate.