Rudy Giuliani, the former New York mayor turned personal attorney to President Donald Trump, could face possible criminal and ethical exposure following the release of a whistleblower complaint, which described him as a "central figure" in alleged efforts to have the Ukrainian government interfere in the 2020 U.S. election, attorneys said last week.

Former federal prosecutors said the complaint, spurred by Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky, laid out troubling allegations that could lead to criminal probes of bribery and extortion and potential disciplinary action against Giuliani.

On Monday, media outlets reported that House committees had subpoenaed Giuliani for documents related to Ukraine as they press ahead with an impeachment inquiry announced in the wake of the whistleblower complaint.

Giuliani, known for his pugnacious style and fierce defense of the president, last week called the whistleblower's account "total nonsense" and strongly rebuffed any allegations of wrongdoing in numerous media appearances. He has maintained that he was acting at the behest of Trump and the State Department, and in one interview held up his phone to suggest he had kept call logs to back up his claims.

Jaimie Nawaday, a former prosecutor in the Southern District of New York, said Giuliani's proximity to the president and State Department officials "doesn't offer him any cover" should prosecutors decide to open an investigation for aiding and abetting and conspiracy to commit bribery and extortion based on the whistleblower's allegations.

While Justice Department policy holds that Trump cannot be indicted while in office, Giuliani is a private citizen and has no such protections, she said.

"There's already talk of criminal exposure for Rudy Giuliani," said Nawaday, a partner with Kelley Drye & Warren. "And there are a lot more facts that are about to come out."

Others, however, were less sure of the likelihood that a U.S. attorney's office would choose to look into the matter. Thomas Kenniff, founding partner of Raiser & Kenniff, said that without evidence of an explicit quid pro quo, the actions described in the whistleblower complaint would not rise to that level.

"I don't think that there's a clear reading that says Trump is offering or withholding a benefit," he said.

Charles Ross, a partner with Mintz & Gold, called Giuliani's alleged behavior "egregious," but said it was not clear that prosecutors would be willing to authorize the resources necessary to launch a criminal investigation. While it was possible, the diplomatic overlays of the case, combined with existing DOJ policy, would make it difficult to ultimately bring conspiracy charges, he said.

"For prosecutors to look at this would be a real stretch," Ross said in an interview.

Still, there was an emerging consensus among the attorneys that Giuliani was vulnerable to potential disciplinary action for possibly running afoul of the New York Rules of Professional Conduct.

Ross and Nawaday both said the public allegations were enough to support the filing of a complaint with an attorney grievance committee, which are appointed by the appellate divisions of the state Supreme Court.

"I don't know that it would rise to the level of extortion," Ross said. "But I think Rudy is exposed to ethical claims."

The issue of standing does not apply to those lodging ethical complaints against lawyers, and anyone who suspects wrongdoing is allowed to avail themselves of the process. A grievance committee could also choose to launch its own sua sponte review based on information that is already publicly available.

In New York, fraud or misrepresentations by attorneys, even in their personal capacities, would qualify as violations of ethics rules, said Richard Maltz of Frankfurt Kurnit Klein & Selz.

"The problem is that we don't know what their thinking is on whether it's sufficient misconduct to warrant the beginning of an investigation," Maltz said.

Any ethics investigation would likely include depositions and document requests, and the accused would be given a chance to respond.

Ultimately, though, it would be up to the committee's chief counsel to decide whether to prosecute the complaint. Were the process to move forward, the appellate division would assign a neutral referee to make factual findings and recommendations to the appellate division, which would make the final decision on public disciplinary measures.

In New York, attorneys can be censured, suspended for a period of up to five years or disbarred for up to seven years. There is no permanent disbarment in the state.

Giuliani's case will likely be compounded by public statements he's made in the following the whistleblower's disclosure.

In the complaint, an anonymous whistleblower from the U.S. intelligence community alleged that Trump had pressured Zelensky to investigate political rival Joe Biden and his son, Hunter Biden, after the two had discussed military aid to Ukraine. According to a summary of the call, Trump encouraged Zelensky to discuss the matter with Giuliani, who the president said "very much knows what's happening."

According to the complaint, Giuliani was in touch with Ukrainian officials in the months leading up to the July phone call, and had traveled to Madrid in August to meet with Zelensky adviser Andriy Yermak as a "direct follow-up" to Trump's conversation with Zelensky.

The whistleblower also cited private statements from U.S. officials, who said they were "deeply concerned by what they viewed as Mr. Giuliani's circumvention of national security decision-making processes to engage with Ukrainian officials and relay messages back and forth between Kyiv and the president."

Trump has denied the existence of a quid pro quo or threatening to withhold aid if Ukraine did not open an investigation into the Bidens.

Giuliani, meanwhile, said in a fiery interview with The Atlantic on Sept. 26 that the State Department had specifically asked for his help, shouting: "If they were so concerned about my activities, why did they ask for my help? Why did they send me a bunch of friendly text messages reaching out for my help, thanking me for my help?"

Attempts to reach Giuliani for comment Sept. 27 were unsuccessful. An assistant initially said he would be available for a phone interview in the afternoon, but multiple calls and texts went unreturned.

Some congressional Republicans on Sept. 27 expressed frustration with the former mayor, as a formal impeachment inquiry got underway in the House. According to reporting by Politico, Sen. John Kennedy, R-Louisiana, said Giuliani was "wild as a March hare," and Sen. Lindsey Graham, R-South Carolina, told reporters: "I'm not sure he's helping the president by being on TV every 15 minutes."

But Nawaday said Sept. 27 that the ramifications of Giuliani's freewheeling media appearances could be more than political.

"The more he goes on TV, and talks about this, the more he imperils himself," she said, noting his tendency to implicate the State Department in interviews. "At this point, it's really hard to understand what he's thinking. It raises so many more questions and points to so many more people who were involved as well."