US President-elect Joe Biden said on Tuesday that nothing would stop the transfer of power in the US government, while President Donald Trump pursued lawsuits in several states in a long-shot bid to hold on to power.

Biden smiled when asked about comments by Secretary of State Mike Pompeo predicting a second Trump administration on Tuesday, as world leaders including British Prime Minister Boris Johnson offered the Democrat congratulations and pledged to work together.

Biden secured the more than 270 votes in the Electoral College he needs to take the presidency by winning Pennsylvania on Saturday after four tense days of counting, which was delayed by a surge in mail-in ballots due to the coronavirus pandemic.

Trump has made baseless claims that fraud was marring the results. Attorney-General William Barr and Senate Republican Majority Leader Mitch McConnell have signaled they back Trump’s right to launch a legal challenge to the result in several battleground states such as Pennsylvania.

Biden said in a speech in Delaware that his team was pushing ahead with forming a new administration to take over on U.S. Inauguration Day, Jan. 20, 2021, no matter what.