A lawyer representing the whistleblower who filed a complaint about Trump’s interactions with Ukraine said over the weekend he is now defending a second intelligence official with more direct knowledge of the matter.

The second whistleblower is considering testifying before Congress. Attorney Mark Zaid told ABC News’ George Stephanopoulos that the inspector general for the intelligence community, Michael Atkinson, has interviewed the second whistleblower over concerns about Trump’s talks with Ukraine’s government. Zaid’s partner Andrew Bakaj confirmed on Twitter that the two lawyers are representing “multiple whistleblowers,” although he did not state an exact number of intelligence officials.

This new development comes as House Democrats ramp up their impeachment probe over Trump’s decision to pressure Ukrainian President Volodymyr Zelensky to investigate Joe Biden and his son in a July 25 phone call. Lawmakers subpoenaed Vice President Mike Pence over the weekend for documents related to the Ukraine controversy.

The White House dismissed reports of multiple whistleblowers by insisting that Trump never committed a crime.

“It doesn’t matter how many people decide to call themselves whistleblowers about the same telephone call,” White House Press Secretary Stephanie Grisham said in a statement. “It doesn’t change the fact that the president did nothing wrong.”

Trump slammed reports of a second whistleblower in a tweet Saturday night in which he made a dig at House intelligence Committee Chairman Adam Schiff by calling him “Shifty:”

Trump famously drew criticism from lawmakers and pundits for tweeting that he had the right to meet the first whistleblower, whom he accused of lying about his interactions with Ukraine. Atkinson said in a statement last week that the president’s claim about the initial intelligence official lacking firsthand knowledge of his talks with the country’s leader was false.

Rep. Jim Himes (D-Connecticut) also commented on the news of a second whistleblower on Monday by dismissing Trump’s claims that only Democrats are after him. Himes emphasized that even people close to the president have voiced concerns over discussions he has held with foreign leaders in which he has asked for favors that benefit him personally or politically.

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“This is not a Democratic-led thing,” Himes said in an interview on CNN. “This is people around the president who have watched his behavior…and are finally saying this can’t happen anymore.”