The chairmen of three House committees subpoenaed Giuliani, who himself serves as President Trump's personal attorney, on Monday for key documents related to the Ukraine controversy as part of their formal impeachment inquiry against the president.
Sale once served as an Assistant Special Watergate Prosecutor. He is also a former Assistant U.S. Attorney in the Southern District of New York.
He has voiced skepticism about previous Democratic-led investigation efforts targeting the White House. Speaking to Fox News earlier this year, Sale called Special Counsel Robert Mueller's Russia probe "totally different" from Watergate, and accused congressional Democrats of "overreacting" by issuing a slew of subpoenas on the matter.
"There was something to cover up" during Watergate, Sale said on Fox & Friends, referring to the Nixon administration's cover up of the 1972 break-in targeting Democratic National Committee headquarters at the Watergate hotel. "Here, there is no underlying crime."
He added: "The ballot box is going to decide whether Trump continues or doesn't continue."
Giuliani, the former New York City mayor, played a key role in seeking information from Ukrainian officials on former Vice President Joe Biden's dealings with the country, along with those of his son Hunter.
The committee chairs subpoenaed Giuliani after claiming he admitted to being "in possession of evidence — in the form of text messages, phone records, and other communications — indicating that you were not acting alone and that other Trump administration officials may have been involved in this scheme."
Giuliani wrote on Twitter Monday evening that the subpoenas seemingly implicated complex questions of attorney-client privilege.
“I have received a subpoena signed only by Democrat Chairs who have prejudged this case," he said. "It raises significant issues concerning legitimacy and constitutional and legal issues including, inter alia, attorney client and other privileges. It will be given appropriate consideration.”
Giuliani has also played a visible role in the White House's strategy of turning the tables on Democrats amid the impeachment inquiry.
Biden's presidential campaign requested in a letter on Sunday that major news networks not invite Giuliani on air anymore, after Giuliani spent the morning on a series of talk shows aggressively highlighting what he called Biden's apparently corrupt dealings in Ukraine and China.
The Biden campaign wrote to NBC News, CBS News, Fox News and CNN to voice "grave concern that you continue to book Rudy Giuliani on your air to spread false, debunked conspiracy theories on behalf of Donald Trump," according to The Daily Beast, which first reported the existence of the letter.
Hours earlier, Giuliani made the rounds on several Sunday shows, including Fox News' "Sunday Morning Futures," to argue that evidence of Biden's possible corruption has been hiding in plain sight for months.
Biden has acknowledged on camera that, when he was vice president, he successfully pressured Ukraine to fire that prosecutor, Viktor Shokin, who was investigating the natural gas firm Burisma Holdings — where son Hunter Biden had a highly lucrative role on the board paying him tens of thousands of dollars per month, despite limited relevant expertise. The vice president threatened to withhold $1 billion in critical U.S. aid if Shokin was not fired.
"Well, son of a b---h, he got fired," Biden joked at a panel two years after leaving office.
Shokin himself had been widely accused of corruption, while critics charged that Hunter Biden might have been essentially selling access to his father, who had pushed Ukraine to increase its natural gas production.
Fox News' Blake Burman and Brooke Singman contributed to this report.