Donald Trump said on Wednesday that if a foreign power offered dirt on his 2020 opponent, he'd be open to accepting it and that he'd have no obligation to call in the FBI.
"I think I'd want to hear it," the US president said in an interview with ABC News, adding: "There's nothing wrong with listening."
The role of Mr Trump's eldest son, Donald Trump Jr., in organising a 2016 meeting with a Russian lawyer offering negative information on Hillary Clinton was a focus of special counsel Robert Mueller's probe of Russian meddling in the last presidential campaign.
Mr Mueller painstakingly documented Russian efforts to boost Mr Trump's campaign and undermine that of his Democratic rival. But while Mr Mueller's investigation didn't establish a criminal conspiracy between Russia and Mr Trump's campaign, Mr Trump repeatedly praised WikiLeaks in 2016 and celebrated information exposed by Russian hackers.
One of Mr Trump's challengers, former Vice President Joe Biden, described Mr Trump's comments as a "threat to our national security".
President Trump is once again welcoming foreign interference in our elections. This isn’t about politics. It is a threat to our national security. An American President should not seek their aid and abet those who seek to undermine democracy.
— Joe Biden (@JoeBiden) June 13, 2019
Several of Trump's other Democratic opponents in the 2020 race, including Senators Elizabeth Warren, Bernie Sanders and Kirsten Gillibrand and former Rep. Beto O'Rourke, repeated their calls to begin impeachment hearings in the wake of the president's latest remarks.
"The #MuellerReport made it clear: A foreign government attacked our 2016 elections to support Trump, Trump welcomed that help, and Trump obstructed the investigation," Ms Warren tweeted.
"Now, he said he'd do it all over again. It's time to impeach Donald Trump."'
Read more: Donald Trump says he would 'want to hear' foreign dirt on 2020 election rivals