A lawyer advising a group of "faithless" Republican electors planning to vote against Donald Trump at the Electoral college has said they won’t be successful in denying him the presidency.

R.J. Lyman has been advising those individually deliberating on their right to break from the majority vote of their state when they cast their votes on 19 December.

However, he said the Electoral College serves as an important democratic check, which the founding fathers would still support today.

“Spoiler alert: in 1789 they anticipated 2016," he told USA today. "They (electors) have to decide whether, in Hamilton’s words, the candidate to whom you are pledged is fit for office."

Electors are voted in by people in their state who are supporting the candidate they want to become president. This process is called the "Electoral College".

There are 538 members and they are expected to vote in line with the majority of voters in their state. Throughout history more than 99 per cent of electors have done so, according to US government figures.

But a group dubbing themselves the "Hamilton Electors" are urging them to ignore their mandates and vote for a candidate other than Mr Trump. It is thought John Kasich, the Ohio governor who has twice made unsuccessful bids for the presidency might be considered as an alternative.

To date, eight "faithless electors" have come forward and said they will vote against their nominee for an alternative candidate. However, only one was from Mr Trump's Republican Party.

"Electors of conscience can still do the right thing for the good of the country," said the lone Republican dissenter Christopher Suprun, as the former firefighter and 9/11 responder announced his intention to rebel.

The other seven are Democrats, casting their votes elsewhere as a form of protest.

Harvard law professor Lawrence Lessig is also offering legal advice to the “faithless electors”.

He is also sceptical the opposition voters will have any sway on Mr Trump’s chances, with only 20 of the 538 members of the Electoral College expected to flip their votes.

Mr Lyman said he wanted to raise awareness of electors’ constitutional rights as Mr Trump, with no government or military experience, prepares to be sworn-in as the US leader.

“I’m not trying to undermine the legitimacy of Donald Trump’s ascendancy to the presidency. I am trying to make sure our institutions function the way they are supposed to,” he said.

“They hold a constitutionally important obligation and every single one I’ve spoken with has understood that issue and that there’s reason for them not simply to follow the majority vote.”

The Republican leader won the presidential race with 306 electoral votes, 36 more than the 270 needed to clinch victory.

37 Republican electors would need to flip their votes in order to deny Mr Trump the presidency.

However, Mr Lyman said many electors have expressed concern over potential legal ramifications for any potential rebellion.

Of the 29 states with “faithless electors’ laws,” only four of them has a specified penalty, he added.

“A number of them are concerned about lawsuits, suing them personally, whether it’s the state party or the presumptive President-elect or his team. These aren’t rich people,” Mr Lyman, who is coordinating a legal defence fund, said.

More than 4.8 million people have signed a change.org petition that urges electors to vote Hillary Clinton.

Ms Clinton’s lead over Mr Trump in the popular vote has soared to 2.8 million.