(This Octpber 9 story corrects Biden quote in fourth paragraph)

ROCHESTER, N.H. (Reuters) - Democratic presidential contender Joe Biden called for the impeachment of U.S. President Donald Trump for the first time on Wednesday in his strongest indictment of the Republican leader’s actions involving Ukraine.

Biden, who figures prominently in the actions that led congressional Democrats to start impeachment proceedings, had refrained from making an outright plea for the move. He said in an opinion piece over the weekend the would let Congress do its job on impeachment.

During a campaign stop in New Hampshire, Biden - the Democratic front-runner for the party’s nomination to run against Trump in the November 2020 election - took the gloves off.

“With his words and his actions, President Trump has indicted himself. By obstructing justice, refusing to comply with a congressional inquiry, he’s already convicted himself,” he said. “In full view of the world and the American people, Donald Trump has violated his oath of office, betrayed this nation and committed impeachable acts.”

“To preserve our Constitution, our democracy, our basic integrity, he should be impeached.”

Trump responded in real time on Twitter, using one of his nicknames for Biden.

“So pathetic to see Sleepy Joe Biden, who with his son, Hunter, and to the detriment of the American Taxpayer, has ripped off at least two countries for millions of dollars, calling for my impeachment - and I did nothing wrong.”

The Democratic-led House of Representatives opened impeachment proceedings against Trump on Sept. 24 over a phone call he had with Ukrainian President Volodymyr Zelenskiy on July 25 in which he asked Zelinskiy to investigate Biden and his businessman son, Hunter Biden.