Donald Trump has not been coy about his ability to undermine Robert Mueller’s Russia investigation. Last month, after news broke that Mueller could be looking into the Trump family’s finances and business deals, The Washington Post reported that the president had begun asking his advisers about his ability to pardon aides, associates, family members, and even himself. The following day, he boasted on Twitter that he has the “complete power to pardon.” Fears that Trump could pre-emptively protect allies from prosecution—or signal to potential witnesses that they should stay quiet—seemed validated when Trump issued a deeply controversial pardon for former Arizona sheriff Joe Arpaio, a close political ally, last week.

Even the suggestion that Trump could issue pardons in the Russia investigation could be a major obstacle for Mueller, who legal experts have suggested is employing a classic anti-mafia prosecution playbook of targeting low-level crimes in order to compel testimony against higher-ups. Mueller, however, has a secret weapon: while the president’s pardon power is absolute, it only applies to federal crimes. In other words, state-level prosecutors could bring charges in the Russia case that would be immune to the presidential pardon. “You would have to find that one of those [election] crimes occurred in New York,” Jennifer Rodgers, a former federal prosecutor in New York, told NBC News. “I don’t think that’s a huge stretch, given that Trump’s people are here—this is where he lived, and his inner-circle lived.”

This appears to be Mueller’s plan. On Thursday, Politico reported that Mueller has teamed up with New York Attorney General Eric Schneiderman’s office. Mueller and Schneiderman have reportedly begun sharing evidence from their parallel probes into Paul Manafort, Trump’s former campaign chairman. Manafort, who has long-standing financial ties to Russian interests, has been a focus in the F.B.I. investigation since last summer, but he has come under heightened scrutiny in recent months. Federal investigators have issued a number of subpoenas to associates of the longtime political operative and at the end of last month conducted a raid on his home, reportedly seeking documents. (Manafort has not been accused of any crime and has repeatedly denied any wrongdoing.)

Prosecutors worried that the possibility of a presidential pardon might allow Manafort to avoid working with investigators. But leaning on Schneiderman’s office to bring charges against the former campaign chairman could force his cooperation. The New York attorney general’s office is also said to be in the early stages of a probe into the Trump Organization’s business transactions. “One of the people familiar with progress on the case said both Mueller’s and Schneiderman’s teams have collected evidence on financial crimes, including potential money laundering,” according to Politico’s Josh Dawsey.

The Mueller-Schneiderman coalition also represents the pairing of two Trump foes. Schneiderman, who on several occasions has found himself on the receiving end of the president’s attacks, won a $25 million settlement against Trump University after a long class-action fraud investigation. The Jared Kushner-owned New York Observer also published a memorably critical hit piece on the New York A.G., in which he was portrayed as a character in the dystopian novel A Clockwork Orange. The 1921 Martin Act gives New York’s top prosecutor additional powers to fight financial fraud, which could make it much easier to build a case.