White House won't say if Trump was joking about China investigating Biden GOP allies dismissed Trump's call to investigate the Biden family as "joking."

With an impeachment inquiry growing on Capitol Hill, the White House on Monday still had not said whether President Donald Trump was joking, as several Republican members of Congress suggested, when he publicly encouraged China to launch a corruption investigation into former Vice President Joe Biden and his family.

“China should start an investigation into the Bidens, because what happened in China is just about as bad as what happened with — with Ukraine,” Trump told reporters on the South Lawn at the White House last Thursday before diving into a defense of his phone conversation with Ukraine President Volodymyr Zelenskiy. “President Zelenskiy — if it were me, I would recommend that they start an investigation into the Bidens. Because nobody has any doubt that they weren’t crooked.”

The White House has not responded to an ABC News inquiry seeking clarification about whether the president's comments were in jest, and the president was not asked about the comment during an event in the Roosevelt Room late Monday.

"The impeachment inquiry is a scam," Trump charged, contending that Pelosi "has made a fool out of herself" by moving ahead with a formal impeachment inquiry. "I had a very very congenial nice conversation with a man that I like and he ran on corruption."

The president added that he believes House Intelligence Chairman Adam Schiff should be investigated for delivering a parody reading of the phone call during a hearing last month, suggesting that Schiff is "having some kind of a breakdown."

"I think it's very sad for our country," Trump said of the inquiry, adding "a lot of people said very few people could handle" the adversity.

"I kind of thrive on it,” he added. “I think it makes it harder to do my job, but I do my job and I do it better than anybody's done it for the first two and a half years based on results."

But after a second whistleblower came forward to support an intelligence official’s initial complaint that the president illegally sought a political in-kind contribution from Ukraine, the president’s closest allies have spent days flatly dismissing the president’s proposal for the Chinese as nothing more than a clumsy joke intended to rile up the press.

"You really think he was serious about thinking that China is going to investigate the Biden family?" Jordan told ABC News Chief Anchor George Stephanopoulos, adding that Trump is “getting the press all spun up” with the prospect. “Remember, this is the president who's been tougher on China than any other president."

That GOP take gained traction late last week when Sen. Marco Rubio reached back into the GOP playbook to dismiss Trump’s call for China to investigate Biden as an effort to provoke reporters.

“I don’t know if that’s a real request or him just needling the press,” Rubio, R-Fla., said. Trump even tweeted video of Rubio’s answer, perhaps suggesting that he wasn’t serious about asking a second country to investigate a political opponent.

But Trump’s apparent willingness to investigate the Biden family’s financial ties to China is not new. During an interview with Fox News’ Steve Hilton on May 19, Trump was asked whether the Biden’s family business in China should be investigated.

“100 percent,” Trump answered. “It's a disgrace."

Mark Zaid, an attorney who represents both whistleblowers, said his second client has already spoken to the intelligence community’s inspector general.

While the date of that conversation remains unknown and it’s unclear whether the second whistleblower has even filed a complimentary complaint, how the inspector general handles that interview could help determine the next steps for Congress.

Republicans and Democrats both hope to have an opportunity to question the whistleblowers in the coming weeks.

“Here’s what I'm going to insist upon, that the whistleblower, one or two, whatever, they come forward, under oath, testify so the public can judge their credibility,” Senate Judiciary Committee Chairman Sen. Lindsay Graham, R-S.C., a staunch Trump ally, said on Fox News Sunday. “If that doesn’t happen in the House I will make sure it happens in the Senate.”

On Tuesday, Gordon Sondland, the U.S. ambassador to the European Union, will answer questions about his involvement in the affair at closed-door depositions before the House Intelligence and Oversight committees.

The first whistleblower, known as a U.S. intelligence official, alleged that Sondland was part of an effort to "contain the damage" done by Trump's personal attorney, Rudy Giuliani, through his efforts to push the Ukrainians toward a Biden investigation.

House Democrats subpoenaed the Defense Department and White House Office of Management and Budget on Monday for information about the withholding of military aid to Ukraine. In a letter to Defense Secretary Mark Esper and Acting OMB director Russ Vought, Reps. Adam Schiff, Elijah Cummings and Eliot Engel set a deadline for the requested records by Oct. 15.

“Pursuant to the House of Representatives’ impeachment inquiry, we are hereby transmitting a subpoena that compels you to produce the documents set forth in the accompanying schedule by October 15, 2019,” the trio of chairmen wrote. “The enclosed subpoena demands documents that are necessary for the Committees to examine this sequence of these events and the reasons behind the White House’s decision to withhold critical military assistance to Ukraine that was appropriated by Congress to counter Russian aggression.”

That subpoena is at least the eighth issued by Democrats in the wake of the whistleblower complaint.

This Friday, Marie “Masha” Yovanovich, a former U.S. ambassador to Ukraine is expected to appear before those three committees at once. She was fired by Trump in the midst of the Trump/Zelenskiy matter.

According to a White House record of the Trump/Zelenskiy July 25 phone call, Trump told Zelenskiy that Yovanovich was “bad news” and that she was “going to go through some things.” Yovanovich was considered highly respected in diplomatic circles but she reportedly tangled with Giuliani.

Republicans are demanding the committee release a transcript of former U.S. Special Envoy to Ukraine Kurt Volker’s closed-door testimony last Thursday before Sondland and Yovanovich are deposed this week.

On Monday, Volker formally resigned from his role as Executive Director at the McCain Institute, hoping to end the distraction caused by questions surrounding documents he provided to investigators, including text messages with other members of the diplomatic community.

“Today, I informed ASU President Crow and Mrs. McCain that I believe the recent media focus on my work as the U.S. special representative for Ukraine negotiations risks becoming a distraction from the accomplishments and continued growth of the Institute, and therefore I am stepping down as Executive Director of the McCain Institute for International Leadership,” Volker wrote in a statement.

Last Friday, the State Department missed a deadline to turn over documents to the committee, but a House Foreign Affairs committee official said the State Department contacted the Committees, creating a level of hope the Department “will cooperate in full promptly.”

Secretary of State Mike Pompeo also publicly pledged to cooperate with the impeachment inquiry, though he dismissed it as a “silly gotcha game.”

“Nations work together and they say ‘Boy, goodness gracious, if you can help me with ‘X,’ we’ll help you achieve ‘Y,’” Pompeo told reporters while traveling in Greece. “This is what partnerships do. It’s win-win. It’s better for each of us.”

Pompeo also defended the president’s interactions with Ukraine, say it is the administration’s “duty” to examine whether efforts to interfere in the 2016 election began in Ukraine.

On Sunday night, the president blasted the second whistleblower and suggested that House Speaker Nancy Pelosi and House Intelligence Chairman Adam Schiff could be guilty of treason due to their pursuit of the facts surrounding the matter. He also suggested that the lawmakers should be impeached, although the constitution does not allow members of Congress to be impeached. Lawmakers may be expelled from office by their fellow lawmakers – but not the president.

Meanwhile, the White House continues to insist that Trump “did nothing wrong” during his conversations with world leaders, and dismissed news that the second whistleblower spoke to the inspector general.

“It doesn’t matter how many people decide to call themselves whistleblowers about the same telephone call—a call the President already made public—it doesn’t change the fact that he has done nothing wrong,” White House press secretary Stephanie Grisham noted.

This whistleblower, also described as a U.S. intelligence official, is believed to have first-hand knowledge of the president’s July 25 phone call with Zelenskiy, which could potentially remove one prong from the White House’s strategic effort to discredit the first whistleblower, because that official only heard certain details about the Zelenskiy call second-hand.

A senior Democratic leadership aide said that there is continued discussion and analysis of whether a vote on the House floor to formally launch an impeachment inquiry would vote protect front-line Democrats.

As House Speaker Nancy Pelosi told ABC News Chief Anchor George Stephanopoulos last week, there is some debate about whether to take the vote to take away GOP’s complaint about restrictions on their rights in the minority and how it’s been the precedent in other recent instances of impeachment in U.S. history.

A senior House Democratic aide told ABC News that there is no requirement under the Constitution, House Rules or precedent that the House take a vote before proceeding with an impeachment inquiry. They argue that a full House vote would only be required on potential articles of impeachment, crafted by the Judiciary committee in the coming months.

A floor vote to approve an impeachment inquiry was not on the table before lawmakers left town for a two-week recess, but Pelosi cracked open the door with her comments during an interview with Stephanopoulos last week, the aide said.

Although there are no plans to schedule a floor vote next week, leadership will likely come together to scrutinize the level of risk in taking that vote when they return to the Capitol next Tuesday.

ABC News' Ben Siegel, John Santucci, Mike Levine, Jonathan Karl and Justin Fishel contributed to this report