Lawyer Mark Zaid said the person, who also an intelligence official, has “first-hand knowledge” of some of the first whistleblower complaint, which triggered impeachment proceedings against the US President. The second whistleblower has been interviewed by the intelligence community’s inspector general, Michael Atkinson, Mr Zaid added. The first whistleblower complaint, filed with the inspector general on August 12, revealed information received from half a dozen US officials expressing concern that Mr Trump was using the power of his office to seek information from a foreign country as he seeks re-election a second term in 2020.
Andrew Bakaj, a second lawyer, said on Twitter: “I can confirm that my firm and my team represent multiple whistleblowers in connection to the underlying August 12, 2019, disclosure to the Intelligence Community Inspector General,”
It also alleged that Trump leveraged $400 million in aid to secure a promise from Ukrainian President Volodymyr Zelenskiy to investigate a Democratic rival, former Vice President Joe Biden.
The investigation also included looking at his son Hunter Biden, who served as a director on a Ukrainian energy company.
Mr Zaid said on Twitter that the second whistleblower “also made a protected disclosure under the law and cannot be retaliated against.”
He told ABC News earlier the second official has been interviewed by the inspector general.
This came after speculation of tensions within Mr Trump’s Republican Party arose after he called on China on Friday to investigate Biden’s son.
This is because he also had business dealings in China.
Republican US Senators Mitt Romney, Ben Sasse and Susan Collins expressed concerns about Mr Trump reaching out to foreign countries to help him in his 2020 re-election bid.
READ MORE: Donald Trump crisis: Democrats subpoena White House for Ukraine papers
She said this was due to the telephone call with Mr Zelenskiy, a summary of which was released by the White House, and the whistleblower complaint.
She added Mr Trump’s attempts to “solicit foreign interference jeopardized U.S. election integrity and threatened national security”.
Democrats said any finding that Mr Trump withheld taxpayer money, already approved by Congress to help Ukraine, in exchange for a favor from Zelenkiy would strengthen the case against him.
Mr Trump has insisted there was no “quid pro quo” in his request of the Ukrainian president, but text messages released by congressional committees leading the inquiry showed otherwise.
The committees released the texts involving Mr Trump’s Ukraine envoy, Kurt Volker, after he testified behind closed doors on Thursday.
The committees are expected to hear this week from another US diplomat, Ambassador to the European Union Gordon Sondland, a committee official confirmed on Sunday.
Mr Sondland worked closely with Mr Volker and Mr Trump’s personal lawyer Rudolph Giuliani on the Ukraine effort.