DES MOINES — U.S. Sen. Chuck Grassley, a long-time defender of whistleblowers and a staunch ally of President Donald Trump, pushed back Tuesday against the president's call to identify the person who filed a complaint about his July phone call with the Ukrainian president.

"This person appears to have followed the whistleblower protection laws and ought to be heard out and protected. We should always work to respect whistleblowers’ requests for confidentiality," the senior senator from Iowa said in a news release.

The president wrote on Twitter on Sunday that he deserves to meet the person who filed a whistleblower complaint about him, saying that they had represented his conversation with Ukrainian President Volodymyr Zelensky in a "totally inaccurate and fraudulent way."

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The whistleblower filed the complaint on Aug. 12 about Trump's conversation with the Ukrainian president, in which the president encouraged the foreign leader to open an investigation into former Vice President Joe Biden, who is running for the Democratic presidential nomination in 2020, as well as Biden's son, who was on an energy company's board in Ukraine.

Trump has sought to delegitimize the report, saying it should not have been filed because much of it is based on second-hand information rather than the whistleblower's direct knowledge of events.

But Grassley, who is chairman of the Senate Finance Committee, pointed out in the release Tuesday that protections for whistleblowers do not hinge on how the person acquired the information they've reported.

“When it comes to whether someone qualifies as a whistleblower, the distinctions being drawn between first- and second-hand knowledge aren’t legal ones," Grassley said. "... Complaints based on second-hand information should not be rejected out of hand, but they do require additional leg work to get at the facts and evaluate the claim’s credibility."

In addition to defending the whistleblower's request for anonymity from the president, he also pushed back against reports on the person's identity from news organizations.

Last week, the New York Times published details on the whistleblower's identity. The paper faced backlash for publishing the information, which critics said could have outed the person's full identity.

"We should always work to respect whistleblowers’ requests for confidentiality," Grassley said. "Any further media reports on the whistleblower’s identity don’t serve the public interest — even if the conflict sells more papers or attracts clicks."

Although Grassley called for protecting the person who filed the whistleblower report, he has not joined with Democrats who are calling for the president's impeachment. The Iowa Republican criticized Democratic House Speaker Nancy Pelosi, who announced the House would launch an impeachment inquiry against the president last week.

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"Unfortunately, instead of waiting to learn the facts by reviewing that transcript or hearing from the whistleblower, Democrats have moved straight to starting the impeachment process," Grassley said in a September news release. "Democrats have been searching for any reason to impeach President Trump since his inauguration because they couldn’t accept the results of the 2016 election."

Grassley has fought throughout his career to extend protections to government whistleblowers, beginning in 1986 when he authored amendments to the False Claims Act encouraging whistleblowers to come forward with reports of fraud and abuse.

Grassley wrote a letter to Trump after he took office in February 2017 urging him to hold a Rose Garden ceremony honoring whistleblowers and their service to democracy.

"Whistleblowers are brave, patriotic people who tell the truth about what is going on in our government," he wrote. "They help us identify waste, fraud, and abuse in the vast and unwieldy federal bureaucracy. When others fight tooth and nail to protect wasteful pet projects, avoid transparency and accountability, and put their own interests ahead of the American people, whistleblowers do exactly the opposite."