UPDATED: 12.45PM (AEDT)

Donald Trump has become just the third president in the history of the US to be impeached after two historic votes in the House of Representatives on Thursday morning (Australian time).

The momentous votes in the Democratic-controlled House on Wednesday (local time) came after eight hours of debate but, in the end, fell almost entirely along party lines, as expected.

The majority vote to impeach Mr Trump on a charge of abusing his office was first, at 12.30pm (AEDT). Just 15 minutes later, it was followed by a vote to impeach the President on a second charge of abuse of his office.

Wednesday’s debate underscored the deep divide in Congress over Mr Trump’s conduct.

Mr Trump is only the third US president to be impeached, after Bill Clinton in 1998 and Andrew Johnson back in 1868. Richard Nixon resigned before he could face the same extraordinary check on presidential power, which is spelled out in the US Constitution for executives who commit “high crimes and misdemeanours.”

No president has ever been removed from office under its terms.

As the vote came, Mr Trump was at a rally in the battleground state of Michigan.

Earlier, the White House had insisted he would be working, rather than focused on the debate in the House. But the President spent his Wednesday morning tweeting, retweeting and expressing disbelief.

“Can you believe that I will be impeached today by the Radical Left, Do Nothing Democrats, AND I DID NOTHING WRONG!,” he wrote in one of 45 tweets posted before noon.

He asked his followers to “Say a PRAYER!”

SUCH ATROCIOUS LIES BY THE RADICAL LEFT, DO NOTHING DEMOCRATS. THIS IS AN ASSAULT ON AMERICA, AND AN ASSAULT ON THE REPUBLICAN PARTY!!!!

— Donald J. Trump (@realDonaldTrump) December 18, 2019

Wednesday’s vote will mean a trial next month in the US Senate in which House members will act as prosecutors. That chamber is controlled by Republicans, who have shown little interest in removing Mr Trump from office.

House Democrats accuse Mr Trump of abusing his power by asking Ukraine to investigate Joe Biden, a former US vice president and a leading Democratic contender in the 2020 election. Mr Trump is also accused of obstructing the congressional investigation into the matter.

Mr Trump has insisted he has done nothing wrong, and on Tuesday called the process “a total sham.” He sent House Speaker Nancy Pelosi a six-page letter in which he accused her of engaging in a “perversion of justice”.

The President has argued Democrats are trying to undo the results of the 2016 election, in which he defeated Democrat Hillary Clinton.

With Mr Trump seeking a second term in 2020, impeachment has cleaved the American public. Most Democratic voters support it and most Republicans are opposed.

Republicans contend that a vote in favour impeachment will cost some moderate House Democrats their seats in next year’s congressional elections. Still, several Democrats who represent districts that backed Mr Trump in 2016 had said in recent days they would vote to impeach him.

On the eve of the vote, Ms Pelosi wrote to all 232 Democratic members of the House, urging them to abide by the Constitution’s standards.

“Very sadly, the facts have made clear that the President abused his power for his own personal, political benefit and that he obstructed Congress as he demanded that he is above accountability, above the Constitution and above the American people,” she wrote.

The Senate has yet to set its procedures for the trial, which will be overseen by US Chief Justice John Roberts.

The chamber’s top Republican, Majority Leader Mitch McConnell, has rejected Democratic proposals to call further administration officials to testify and has said there is “no chance” Mr Trump will be removed from office.

Removing Mr Trump from office will require a two-thirds majority of those present and voting in the 100-member chamber. That means Democrats have to persuade at least 20 Republicans to join them to end Mr Trump’s presidency.

-with AAP