Former US Vice-President Joe Biden has made his first call for President Donald Trump’s impeachment.
The Democratic front-runner in the 2020 presidential race told a rally that Mr Trump had “violated his oath of office” and “committed impeachable acts”.
Democrats have launched an impeachment inquiry over claims that Mr Trump illegally pressured a foreign leader to investigate Mr Biden and his son.
Mr Trump denies wrongdoing and has dismissed the probe as a “witch hunt”.
On Tuesday the White House said it would not co-operate, arguing that the proceedings were unconstitutional.
Addressing supporters in New Hampshire on Wednesday, Mr Biden said: “President Trump has indicted himself by obstructing justice, refusing to comply with a congressional inquiry. He’s already convicted himself.”
It was his most forceful response to date.
Previously, the former vice-president had only gone so far as to back an inquiry to gather the facts, even as his top Democratic rivals were calling for impeachment.
Shortly after Mr Biden spoke, Mr Trump hit back at “Sleepy Joe Biden” and his “failing campaign”.
Why is there an impeachment inquiry?
The Democratic-led inquiry is trying to establish whether the Republican president withheld nearly $400m (£327m) in aid to nudge Ukraine’s president into launching an inquiry into Mr Biden and his son.
Hunter Biden was on the board of a Ukrainian energy company, Burisma.
In a phone call on 25 July, Mr Trump asked the newly elected Volodymyr Zelensky to scrutinise the former US vice-president, who is a leading Democratic contender for next year’s White House election.
A whistleblower raised concerns about the phone call, and the Democratic leader of the House of Representatives, Speaker Nancy Pelosi, announced a formal impeachment investigation last month.
When Hunter Biden joined the firm in 2014, questions were raised about a potential conflict of interest for his father.
But there is no evidence of wrongdoing on the part of the Bidens.