WASHINGTON — House Intelligence Committee Chairman Adam Schiff said Sunday it’s possible the U.S. intelligence whistleblower whose complaint triggered an impeachment inquiry into President Donald Trump will not testify before lawmakers as previously planned, citing concerns about the safety of the individual and that of a second whistleblower who has since come forward.

Schiff (D-California), appearing on CBS’ “Face the Nation,” said the panel’s “primary interest right now” is making sure the pair of whistleblowers remain protected as provided under federal law.

Trump has repeatedly called for identity of the original whistleblower to be released and has likened the individual and those unnamed White House officials cited in the whistleblower’s complaint to “spies.”

“Given that we already have the call record, we don't need the whistleblower who wasn't on the call to tell us what took place during the call. We have the best evidence of that,” said Schiff, referring to a summary transcript released by the White House of Trump’s July 25 call with Ukrainian President Volodymyr Zelensky.

Trump, according to the White House summary of the call, pressed Zelensky for a “favor,” urging him to investigate his political rival, former Democratic Vice President Joe Biden and his son Hunter. The president has said the request was “perfect,” but House Democrats have argued the call was an illicit attempt by the president to use his office to encourage foreign influence over the upcoming 2020 presidential election. The call came days after Trump ordered the suspension of nearly $400 million in U.S. military aid to Ukraine.

“We do want to make sure that we identify other evidence that is pertinent to the withholding of the military support, the effort to cover this up by hiding this in a classified computer system,” Schiff said. “We want to make sure that we uncover the full details about the conditionality of either the military aid or that meeting with Ukraine's president. It may not be necessary to take steps that might reveal the whistleblower's identity to do that.”

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Schiff’s appearance came as Congress prepares to reconvene on Tuesday after a two-week recess. House Democrats worked on the inquiry during the break, deposing the former U.S. special envoy to Ukraine, Kurt Volker, and the former U.S. Ambassador to Ukraine Marie Yovanovitch, while issuing a series of subpoenas to Trump administration officials and associates, including his personal attorney Rudy Giuliani and Secretary of State Mike Pompeo.

Rep. Lee Zeldin (R-Shirley), appearing on ABC’s “This Week,” vigorously defended Trump’s request of Ukraine.

Asked if he believed it was appropriate for Trump to ask Zelensky to investigate the Bidens, Zeldin said: “I absolutely believe that our countries should be working together to get to the bottom of what happened.”

Trump has raised questions about Hunter Biden’s role serving on the board of a Ukrainian natural gas company, Burisma, while his father was in office. The former vice president and 2020 Democratic presidential candidate has said he and his son never discussed his business dealings. While government ethics groups have raised concerns about the appearance of the arrangement, Ukraine’s current and former top prosecutors have said there is no evidence of wrongdoing committed by the Bidens.

The president has since publicly called on China to investigate the Bidens. Amid the scrutiny of his foreign work, Hunter Biden on Sunday announced through his lawyer that he is stepping down from the board of a Chinese-backed private equity firm and promised he would turn down foreign business opportunities if his father is elected president in 2020.

Sen. Ted Cruz (R-Texas), appearing on CBS’ “Face the Nation,” said it was “of course not” appropriate for Trump to make such a request of China.

“Elections in the United States should be decided by Americans, and it’s not the business of foreign countries to be interfering in our elections,” Cruz said.