Trump opponents circulating online petitions to beat him at the Electoral College

Grassroots campaigns have sprung up around the country to try to persuade members of the Electoral College to do something that has never been done in American history, deny the presidency to the clear Election Day winner.

Activists are circulating online petitions and using social media in hopes of influencing Republican electors to cast their ballots for someone other than President-elect Donald Trump and deprive him of the 270 Electoral College votes needed to become the next occupant of the White House.

"Yes, I think it's a longshot, but I also think we're living in strange times," said Daniel Brezenoff, who created a petition in favour of Hillary Clinton and is asking signers to lobby electors by email or phone. "If it was ever plausible, it's this year."

Trump has won 290 electoral votes to Clinton's 232, with Michigan undecided, but Clinton is on pace to win the popular vote by at least 1 million ballots. Trump's opponents are motivated by the outcome of the popular vote and by their contention that the businessman and reality TV star is unfit to serve as commander-in-chief.

Just one elector so far has wavered publicly on supporting Trump.

Texas Republican Art Sisneros says he has reservations about the president-elect, but not because of the national popular vote. He told The Associated Press he won't vote for Clinton under any circumstance.

"As a Christian, I came to the conclusion that Mr Trump is not biblically qualified for that office," he said.

He said he has heard from ecstatic Clinton supporters and even supportive Republicans, but also from outraged Trump backers writing "threatening and vile things."

Sisneros signed a state party pledge to support the GOP's standard-bearer, but that was before Trump was the official nominee. He said one of his options is to resign, allowing the state party to choose another elector.

Electors are chosen by party officials and are typically the party's most loyal members. Presidential electors are not required to vote for a particular candidate under the Constitution. Even so, the National Archives says more than 99 per cent of electors have voted as pledged throughout the nation's history.

Some state laws call for fines against "faithless electors", while others open them to possible felony charges, although the National Archives says no elector has ever been prosecuted for failing to vote as pledged. In North Carolina, a faithless elector's vote is cancelled, and he or she must immediately resign and be replaced.