Protesters have again taken to the streets of some cities in the United States as the electoral college ratified the election of Donald Trump as the 45th President, despite a last-ditch effort to deny him the White House.

Millions of Americans signed an online petition stating that Trump was unfit for the Oval Office, while anti-Trump protesters gathered at state capitals across the country.

In Pennsylvania, more than 200 demonstrators braved sub-zero temperatures, chanting: “No treason, no Trump!'”

In Maine, protesters beat drums and waved signs saying: “Don’t let Putin Pick Our President.”

Six weeks after winning the presidential election, Trump cruised past the 270 electoral college votes needed to formalise his victory.

Reacting, Trump promised to “work hard to unite our country and be the president of all Americans”.

Electors had been flooded with emails and phone calls urging them not to support the billionaire.

But despite long shot liberal hopes of a revolt by Republican electors, only two – from Texas – ended up voting against him.

It was the Democratic candidate who ended up losing more electoral votes in Monday’s ballot at state capitals nationwide.

Five of Democratic Party electors defected, with three voting for ex-Secretary of State Colin Powell, one for a Native-American tribal leader and another for Vermont Senator Bernie Sanders.

The result will be officially announced on January 6 in a special joint session of Congress.

“I thank the American people for their overwhelming vote to elect me as their next president of the United States,” Trump said in a statement after the result came in.

“With this historic step we can look forward to the bright future ahead.”

The voting process is usually a formality, but was overshadowed this year by claims that Russian hackers tried to sway the presidential election.

Numerically, Trump’s opponents never stood much chance. To keep him out of the Oval Office, 38 Republican electors would have had to defect.

Even that would probably only have delayed the inevitable.

If no candidate had reached 270 in the Electoral College, the House of Representatives would have voted on the next president.

The Republican-controlled chamber would most likely have picked Trump.

The President-elect is due to take office on 20 January.