US Democratic nominee Hillary Clinton's popular lead over President-elect Donald Trump surpassed 2.5 million votes as ballots are still being tallied after more than three weeks since the November 8 election.
According to local media reports, Clinton's lead in total votes over Trump now is larger than the lead with which as many as ten US presidents have won the general election.
Converted into percentages, Clinton has won 48.1 per cent of the vote so far, while Trump's share of the vote so far is 46.4 per cent, Xinhua news agency reported.
However, it was Trump who prevailed on Election Day by clinching crucial 270 Electoral College votes. He has 306 Electoral College votes to Clinton's 232.
Trump tweeted on Sunday that he would have won the popular vote if millions of people didn't vote "illegally", but failing to offer any evidence to support his claim.
Green Party candidate Jill Stein has filed for vote recounts in three swing states -- Wisconsin, Pennsylvania and Michigan, an effort supported by Clinton's campaign but called a "scam" by Trump.
Only in the highly unlikely event of overturning all three states can Clinton beat Trump to the White House.
Trump won all three states by a narrow margin in the presidential election, leading his major rival Democrat Hillary Clinton with just over 100,000 votes in all three states.
US electors will meet on December 19 to certify the results of the Electoral College.