Manhattan District Attorney Cyrus Vance Jr.'s office was prepared to bring state criminal charges against former Trump presidential campaign manager Paul Manafort, according to media reports that surfaced Friday. But any case brought by state prosecutors under New York law would have to clear a big hurdle—the prohibition on double jeopardy.

Manafort is scheduled to be sentenced in two separate federal cases next month. He was found guilty on eight financial fraud related counts by a federal jury in Virginia last August. He subsequently pleaded guilty to separate charges in Washington, D.C., in September.

The effort being prepared by Vance's office, reports said, is framed as making sure Manafort will be held accountable for his crimes, even if he should be pardoned by President Donald Trump.

The ability to bring New York state charges against Manafort isn't as easy as simply convincing a grand jury. The attorney general's office claimed last year in a pitch to state lawmakers that, unless the state's double jeopardy law was changed, state prosecutors would be blocked from doing exactly what Vance's office is reportedly headed toward.

State Sen. Todd Kaminsky, D-Nassau, sponsors legislation to close the so-called double jeopardy loophole. He said any case brought by Vance's office against Manafort will likely be challenged right off the bat over the state's laws and that his bill would make such an argument moot.

“If this bill or something like it would be law, we would have clarity and these situations in the future would not arise,” Kaminsky said. “I have no doubt that whatever the Manhattan DA's office is going to bring is going to face a serious double-jeopardy challenge.”

Attorney General Letitia James has stated her support for the efforts made by her predecessors. She campaigned on the issue during last year's race to become the state's top lawyer and even lobbied on its behalf when she traveled to Albany earlier this month.

“We're in the midst of discussions with the Assembly, and we hope to be announcing something very soon,” James said during an interview before she met with Cuomo and lawmakers last week.

No such announcement has been made as of yet, but Kaminsky said on Friday that they're making progress on bringing the bill to the floor for a vote.

“We're all working through language that the Assembly is hoping to see, that would make the bill a little more narrow but acceptable,” Kaminsky said.

Begun initially by former Attorney General Eric Schneiderman and continued by his successor, Barbara Underwood, the AG's office used pardons by Trump to illustrate what the office claims is Trump's use of the pardon power to “thwart the cause of justice, rather than advance it.”

“We can't afford to wait to see who will be next,” Underwood warned in May. “Lawmakers must act now to close New York's double jeopardy loophole and ensure that anyone who evades federal justice by virtue of a politically expedient pardon can be held accountable if they violate New York law.”

Kaminsky echoed that warning during an interview on Friday.

“There are future 'Manaforts' out there and every day we are not passing this bill, we get one step closer to people being able to use a double jeopardy defense if a federal case is brought against them first,” Kaminsky said.

According to a letter from the AG's office in April 2018, state law offers strong protections against prosecutions by state officials for identical acts or offenses already pursued by another jurisdiction. If a defendant pleads guilty to federal crimes or proceeds to a federal jury trial, then state prosecution is barred based on the same acts or criminal transactions.

While there are exceptions to the statutory language in the event of nullification of criminal proceedings by the courts, there appears to be none on the books in the case of the President of the United States doing so.

According to Bloomberg News, which first reported the Manhattan DA's plans, Vance's team has been investigating Manafort since 2017. The local prosecutors are fully aware of the restrictions posed by the double jeopardy law and are actively seeking to get around them, according to the reports. For example, Vance could proceed with state charges of falsifying books and records related to Manafort's manipulation of bank records for which special counsel Robert Mueller III brought federal bank fraud charges.

A spokesman for the Manhattan DA's office declined to comment on the media reports.

Some observers familiar with the debates within the AG's office aren't so sure Vance will be able to clear that hurdle, despite the reported confidence. Eric Soufer, a former top aide to both Schneiderman and Underwood, took to Twitter to air his concerns. According to him, the office “drilled down on this issue with some of the best criminal prosecutors in the business.”

“The consensus? There's almost no way to bring state charges against someone at state level after they've been tried at fed level for analogous crimes,” Soufer wrote.

Kaminsky said it's possible that state prosecutors could bring charges against Manafort that weren't brought up during last year's wide-ranging criminal trial in the Eastern District of Virginia. Vance's office could focus on charges brought in relation to certain lenders that were not alleged in the federal case, for example, or they may be able to bring a tax fraud case against Manafort, Kaminsky said.

But those charges are minimal compared to what could be brought if the state's double jeopardy laws were changed, he argued.

“There are narrow ways they can think about carving it up,” Kaminsky said. “But we're really asking prosecutors to basically try to crawl through the 3-foot-high tunnel in order to get through the past, so to speak, and I think it's unfortunate and this is assuming it survives a challenge.”

The legislation has stalled among Democrats who want to see it written more narrowly to avoid situations where it could backfire. The intent would be to allow state prosecutors to bring charges in major cases, like Manafort's, not smaller cases where a future president pardons someone of a low-level crime.

Kaminsky said, if anything, the news that Vance's office has prepared a case is all the more reason for lawmakers to coalesce around his bill.

“Despite the Manhattan DA's ingenuity and figuring out a way through, I nevertheless still think this greatly highlights the double jeopardy loophole bill we're trying to get through the Legislature,” Kaminsky said.

A spokeswoman for the AG's office did not respond to a request for comment.