The US House of Representatives has voted to advance the impeachment inquiry against Donald Trump. Photo / AP
US President Donald Trump has been dealt a major blow after the sharply divided House of Representatives voted to advance the impeachment inquiry against him on Thursday.
It was the chamber's first formal vote on the process, which passed 232 to 196, but it doesn't mean the US leader is impeached just yet.
The investigation is likely to take months and could possibly stretch into the early weeks of the 2020 election year.
The vote was a victory for majority Democrats, who will control the investigation in the House. It gives them the ability to curb the ability of Republicans to subpoena witnesses and of White House lawyers to present witnesses.
"Today the House takes the next step forward as we establish the procedures for open hearings... so that the public can see the facts for themselves," House Speaker Nancy Pelosi said.
But Republicans said the process was skewed against them and the White House.
Trump called it "the greatest witch hunt in American history", while White House press secretary Stephanie Grisham accused Democrats of having an "unhinged obsession with this illegitimate impeachment".
"Democrats are choosing every day to waste time on a sham impeachment – a blatantly partisan attempt to destroy the President," she said in a statement.
Trump faces becoming the third president in history to be impeached and placed on trial for removal in the Senate over an alleged extortion scheme to obtain Ukraine's help to get him re-elected in 2020.
He is accused of withholding military aid to compel Ukraine to mount an embarrassing corruption probe against his Democratic election rival Joe Biden, using US foreign policy in an illegal shakedown for his personal political benefit.
Trump says the case is cooked up, but congressional investigators have heard a steady flow of corroborating evidence from government officials testifying behind closed doors on Capitol Hill.
The approved legislation moves the inquiry into the public eye, giving Americans the chance to hear on live television the evidence against him.
The next phase will see open evidentiary hearings in the House Intelligence Committee, which has led the inquiry so far, presenting witnesses and documentary evidence and allowing Republicans to challenge the evidence.
The case would then go to the House Judiciary Committee, where Trump and his lawyers will be able to challenge the evidence and submit their own.
If the case against Trump is deemed strong enough, the committee will draw up formal charges against the president – articles of impeachment – to be voted on by the entire House.
That process could be completed within the final months of this year. The Democrat-controlled House is expected to pass the articles, which would then see Trump go on trial for removal in the Senate, where Republicans have a majority.
"We are not here in some partisan exercise. We are here because the facts compel us to be here," said Jim McGovern, chairman of the House Rules Committee which drew up the impeachment process legislation.
"There is serious evidence that President Trump may have violated the Constitution. This is about protecting our national security and safeguarding our elections," he said on the house floor.
"If we don't hold this president accountable, we could be ceding our ability to hold any president accountable," he said.
Nearly a dozen witnesses so far have confirmed in House interviews the accusations that in a concerted effort with top aides and his personal lawyer, Trump pressured Ukraine to help his re-election effort in 2020 by producing dirt on Biden, the former vice president.
The allegations focus on a July 25 phone call in which Trump pressed Ukraine President Volodymyr Zelensky to open investigations into Biden and his son, who had close ties to a Ukraine energy firm.
Asking for a "favour" in the same call, Trump also pushed Zelensky for an investigation to find evidence in support of conspiracy theories that hold that Kiev assisted Democrats against Trump in the 2016 election.
Early on Thursday, Tim Morrison, the White House National Security Council's top Russia expert, arrived on Capitol Hill for his testimony.
According to other witnesses, Morrison, who resigned on Wednesday, has personal knowledge of the White House's effort to freeze A$567 million in military aid to Ukraine to pressure Zelensky to launch the political investigations.
The investigators also have called on Trump's estranged former national security adviser John Bolton to testify next week, along with two White House national security lawyers.
Bolton, other witnesses have said, disagreed strongly with Trump's tactics toward Ukraine and the involvement of his personal lawyer Rudy Giuliani in Ukraine policy.