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WASHINGTON - US President-elect Donald Trump on Monday officially won the 270 electoral votes needed for White House in the on-going 538-member US Electoral College voting which is to end later on the day, US media reported.

Texas' 36 electoral votes for Trump pushed him over the edge at around 4:30 pm central time, said a TheHill news daily report.

The electors, chosen by their state political parties, are convening on Monday in Washington D.C. and statehouses across the country to cast two votes -- one for president and one for vice president.

So far almost all the Republican electors stayed loyal to their candidate, despite turmoil fuelled by the CIA conclusion that Russia intervened the US election partly in bid to harm Trump's Democratic rival Hillary Clinton.

Though the former secretary of state takes a lead over Trump by nearly three million popular votes up to now, Trump is projected to win more than 300 electoral votes.

The number of electors each state has is equal to its number of representatives and senators in Congress -- 538 in total, with those extra three electors coming from Washington District of Columbia. Among them are state party leaders, elected officials or just individuals with a personal connection to a presidential candidate.

The Congress, where the Republican hold a strong majority, will certify the vote on Jan 6.