An attorney for the anonymous whistleblower, who filed a complaint about President Donald Trump's call with Ukrainian President Volodomyr Zelensky, tweeted in 2017 about a "coup" and "rebellion" against Trump, according to Fox News.

The attorney, Mark Zaid, wrote the tweets after the firing of former Attorney General Sally Yates, an Obama-era official who refused to defend federal laws in court.

"Coup has started," Zaid wrote in January 2017. "First of many steps. #Rebellion. #Impeachment will follow ultimately."

"45 years from now we might be recalling stories regarding the impeachment of @realDonaldTrump," Zaid wrote in June 2017. "I'll be old, but will be worth the wait."

Zaid is openly opposed to President Trump, and has openly courted whistleblowers to expose dirt on the president on Twitter. Now, it appears, he has succeeded, as the whistleblower he represents issued a complaint that is now one of the foundational pieces of an impeachment inquiry.

The attorney also tweeted in July 2017 that he believed "CNN will play a key role in [Trump] not finishing out his full term as president."

The whistleblower's identity, political views, and motives have become sources of heavy speculation as Democrats seek to protect his identity and Republicans increasingly push to expose it in order to present the impeachment effort as a coordinated effort to overturn the 2016 election result.

With public impeachment inquiry hearings set to start next week in the House Intelligence Committee, House Republicans have issued a subpoena to have the whistleblower testify — a request that will likely be vetoed by the Democrats, who have authority over who testifies as the majority party.

"The president's allies would like nothing better than to help the president out this whistleblower," Rep. Adam Schiff (D-Calif.) said last week. "Our committee will not be a part of that. They have the right to remain anonymous. They certainly should not be subject to these kinds of vicious attacks."