A second whistleblower has come forward with information about President Donald Trump’s call with the president of Ukraine, according to attorneys representing that whistleblower and the intelligence official whose earlier complaint set off a series of events that led to an impeachment inquiry.

The second whistleblower "has first-hand knowledge" of the events, according to the first whistleblower's attorney, Mark Zaid. The original whistleblower did not listen directly to Trump's call, but talked to people who had.

The first complaint, filed in August with the intelligence community's inspector general, centered on a July 25 phone call during which Trump asked Ukrainian President Volodymyr Zelenskiy to look into why Ukraine's top prosecutor had apparently ended an investigation into a Ukrainian gas company that once employed former Vice President Joe Biden's son as a board member. House Democrats launched the formal impeachment inquiry last month as details of the conversation were made public.

Legal sources told NBC News that the second whistleblower is not filing a separate formal complaint, but that they are still entitled to legal protections for cooperating with the inspector general.

Trump has publicly maintained that the call was "absolutely perfect" and "totally appropriate."

"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 said Sunday.

Text messages given to Congress on Thursday and released by House Democrats suggest the call was part of a broader effort from Trump and his administration to pressure Ukraine.

The texts show U.S. ambassadors working to persuade Ukraine to publicly commit to investigating Trump’s political opponents and explicitly linking the inquiry to whether Ukraine’s president would be granted an official White House visit.

The messages offer the fullest picture to date of how top diplomats and Trump's personal lawyer Rudy Giuliani sought to advance Trump’s goal of getting the Ukrainians to investigate both meddling in the 2016 election and Hunter Biden.

The new details on how Trump’s pressure campaign on Ukraine unfolded came as the president publicly called for another country — China — to probe one of his top political opponents.

Trump and his top allies have brushed off reports about the second whistleblower.

"The first so-called second hand information 'Whistleblower' got my phone conversation almost completely wrong, so now word is they are going to the bench and another 'Whistleblower' is coming in from the Deep State, also with second hand info," Trump tweeted Saturday. "Meet with Shifty. Keep them coming!"

In an appearance on "Fox News Sunday," Rep. Chris Stewart, R-Utah, said the latest whistleblower "does not matter."

"This person is going to come forward and say, yep the president had this phone call," Stewart, a member of the House Intelligence Committee, said. "And yep, that's the transcript. Why should I care at all what his opinion and judgment of this transcript is? You and I can read it."

A White House summary of the July phone conversation, released last month, does not contradict the whistleblower complaint. The summary showed that Trump and Zelenskiy discussed military aid the U.S. provides Ukraine before Trump asked his counterpart for "a favor." The president then asked Zelenskiy to investigate theories regarding Ukraine's involvement in the 2016 election and the Biden family.

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In a formal complaint, the first whistleblower detailed how White House officials were so concerned about what the president said in that call that they intervened to "lock down" the record of the conversation. The whistleblower filed the complaint, which relied on the accounts of White House and other U.S. officials, out of a belief Trump was "using the power of his office to solicit interference from a foreign country" in the 2020 election.

Trump has referred to the first whistleblower as "fake," adding that the complaint was "not holding up," though it was deemed credible by a Trump-appointed intelligence community inspector general, and was authored by someone who the Trump-appointed acting Director of National Intelligence Joseph Maguire told Congress last month had acted in "good faith."

The president and his supporters have zeroed in on Biden's 2016 call, backed by much of the international community, to remove Viktor Shokin, the Ukrainian prosecutor. Shokin, who had been widely accused of not doing enough to crack down on corruption, had been investigating Burisma, the scandal-plagued energy company affiliated with Hunter Biden. But earlier this year, Bloomberg News, citing documents and an interview with a former Ukrainian official, reported the Burisma investigation had been dormant for more than a year by the time Shokin was fired. In addition, former Ukrainian Prosecutor General Yuriy Lutsenko has told news outlets he found no evidence of wrongdoing by Biden and his son.

Appearing on NBC's "Meet the Press," Sen. Chris Murphy, D-Conn., said Republicans were going to "wild lengths" to avoid criticism from Trump.

"They shouldn’t be fearful of this president," he said. "If they vote to get rid of him, there’s nothing he can do to hurt them."

The Office of the Inspector General of the Intelligence Community declined to comment to NBC News on Monday regarding the existence of another whistleblower.