Giuliani expected to 'spill damning secrets' about Trump to 'save himself': ex-federal prosecutor
Former Mayor Rudy Giuliani of New York City speaking to supporters at an immigration policy speech hosted by Donald Trump at the Phoenix Convention Center in Phoenix, Arizona. (Gage Skidmore)

Former federal prosecutor Renato Mariotti explained over the weekend why Rudy Giuliani will likely be left with no choice but to provide evidence against former President Donald Trump.

In a Sunday column for Politico, Mariotti noted that federal agents may be examining whether Giuliani was acting at the behest of Ukrainian officials when he urged Trump to oust then-ambassdor to Ukraine Marie Yovanovitch.

"If Giuliani's efforts to push Trump to fire Yovanovitch were done on behalf of Ukrainian officials, that could be the sort of foreign lobbying activity that he should have disclosed," Mariotti wrote.

The former federal prosecutor observed that an indictment of Giuliani could mean that it's too late for Trump.

"At that point, he will need to adopt a defense strategy that may put him at odds with his former client," he said, noting that Trump would be unlikely to testify on behalf of Giuliani.

"That would make him worthless for Giuliani as a witness and force Giuliani to point the finger at Trump to save himself," Mariotti continued. "The five-year sentence Manafort received for conspiring to violate [the Foreign Agents Registration Act] FARA gives Giuliani ample incentive to do so, especially since he knows Trump cannot pardon him any longer."

"When a lawyer, particularly a famous former federal prosecutor like Giuliani, faces time in prison, the incentive to reduce that sentence is significant," the former prosecutor added. "Just like Michael Cohen, Giuliani will have every incentive to help federal prosecutors if it could potentially reduce his prison sentence. That could make the Giuliani prosecution far more consequential than it appears at first glance, given his role in everything from the defense of Trump's impeachment to the Jan. 6 insurrection."

"Without Trump's protection or financial support, Giuliani's loyalty would seem to have a limited shelf life."