Former GOP Rep. Joe Walsh, a longshot candidate for the Republican nomination for president, on Sunday called President Donald Trump a "traitor" for asking Ukraine and China to investigate former Vice President Joe Biden and his son, Hunter, and again argued Trump should be impeached for asking other countries to "interfere in our election."

"There's enough we know now to vote to impeach this President. He stood on the White House lawn this week, Jake, and told two additional foreign governments to interfere in our election. That alone is impeachable. This is a strong term I'm going to use. But I'm going to say it on purpose: Donald Trump is a traitor," Walsh, who represented Illinois, told CNN's Jake Tapper on "State of the Union."

The strong comments from the former Republican congressman come as Trump faces a widening impeachment inquiry in the House of Representatives. Most current congressional Republicans have remained silent and declined to speak out in opposition to the President's comments last week that he wants both Ukraine and China to investigate Joe Biden and his son, Hunter. Walsh had previously said he supports Trump's impeachment and said again on Sunday that congressional Republicans should also "get behind" it.

There is no evidence of wrongdoing by either Joe or Hunter Biden.

Walsh told Tapper that he is "not accusing this President of treason," but he said Trump has betrayed the nation.

"Our founders were very specific as to what treason is. But when you look at traitor more broadly defined, this President betrayed our country again this week," Walsh said.

During a contentious exchange with Walsh on the same program, former Republican Rep. Mark Sanford, who is also seeking his party's 2020 presidential nomination in a longshot bid, disagreed with Walsh's steadfast support of impeachment, saying that "the nature of a process is not to come to the conclusion at the beginning of it."

"I do think we ought to be incremental. Are there very troubling charges out there? Yes. Do they need to be investigated? Yes. But to jump to conclusion and say (Trump) needs to be impeached, what he's done is treasonous, is to say we're not going to go through the very process that the founding fathers laid out," said Sanford, who represented South Carolina.

Sanford, pressed by Walsh on whether Trump's actions warrant impeachment, said their thoughts are "irrelevant to the process that's at play" and that they have to look at the "costs" of the impeachment process, which he said includes a shift in focus from the 2020 election to the impeachment process.

House Democrats are pressing forward with the impeachment inquiry centered on Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky, and on Friday issued a subpoena to the White House and a documents request to Vice President Mike Pence.

Trump has faced limited criticism from members of his own party, but a rebuke from Republican Sen. Mitt Romney of Utah on Trump's call for the other countries to investigate drew a crude attack from the President on Saturday.