The attorney for Lev Parnas, the ex-Rudy Giuliani associate now charged with federal campaign-finance violations, told Law.com affiliate the New York Law Journal on Thursday his client wants to tell his story to Congress in an effort, partly, to mitigate any sentence he might receive in federal court.

Joseph Bondy, Parnas' Manhattan-based criminal defense counsel, said his client and federal prosecutors are at an impasse, after earlier attempts to provide information to the Manhattan U.S. Attorney's Office were rebuffed.

Parnas, whose work in Ukraine landed him at the center of the presidential impeachment inquiry, was "trying very hard" to be a congressional witness at Trump's Senate impeachment trial, which is scheduled to start in earnest next week, he said.

"In the event that there ever was a conviction, the hope would be that his efforts in providing substantial assistance to Congress would warrant a reduced sentence," Bondy told the Law Journal.

Prosecutors in the Southern District of New York, he said, had refused Parnas' earlier proffers related to charges that he had funneled foreign money into U.S. elections, and Parnas was now prepared to take his story public in the hope that it could help his criminal case.

Southern District prosecutors would be unlikely to agree to a downward variance in sentencing, but a federal judge in sentencing could consider any help Parnas potentially gives to Congress.

Parnas, a Soviet-born associate of Giuliani, in an interview with MSNBC's Rachel Maddow on Wednesday implicated Trump, Vice President Mike Pence and U.S. Attorney General William Barr in the wide-reaching effort to dig up damaging information on Democratic presidential candidate and former Vice President Joe Biden.

The second part of Parnas' sit-down with Maddow is slated to air Thursday night, along with an interview he recorded Wednesday with Anderson Cooper.

According to Parnas, Trump and others in the administration "knew exactly what was going on," while Parnas was "on the ground, doing their work."

Trump, Pence and the Justice Department have all denied the allegations.

The U.S. Attorney's Office for the Southern District of New York did not immediately provide comment Thursday night.

Parnas was arrested in October at Washington Dulles International Airport with a one-way ticket while waiting to board a plane with a one-way ticket to Vienna.

Prosecutors alleged in a 21-page indictment that Parnas and fellow Giuliani associate Igor Fruman made illegal donations to buy political influence and then worked to conceal their scheme from candidates, campaigns and federal regulators by laundering money through bank accounts in the names of limited liability companies and through the use of straw donors.

Both Parnas and Fruman have pleaded not guilty to four counts of conspiracy, falsification of records and making false statements to the Federal Election Commission.

Parnas, who has repeatedly maintained his innocence, has been signaling that he wants to be subpoenaed in the impeachment inquiry, and Bondy recently won a court order from U.S. District Judge Paul Oetken of the Southern District of New York allowing the defense to turn over records to congressional investigators.

Bondy, meanwhile, has accused prosecutors of "slow-playing" production of discovery materials and said Thursday that he was ready to take the criminal case to a more public phase.

"I am not going to be tied down by the Southern District," he said.

Parnas' explosive comments, on the eve of the impeachment trial, stirred speculation about the strategy behind Parnas' ongoing media blitz.

Sources contacted Thursday said the public campaign appeared to be part of a concerted strategy to gain a foothold with prosecutors overseeing his case or, failing that, to lay the groundwork for congressional testimony in a bid for leniency in his sentencing, if he is ultimately convicted on the charges.

It was seen as unlikely that the move would succeed in reopening talks aimed at securing any kind of a cooperation agreement with prosecutors, which could potentially limit his exposure to criminal charges.

The Southern District is known for its hard-line policy, which requires would-be cooperators to admit to all crimes they may have committed, even those the government does not know about. The demanding nature of the process is designed to allow prosecutors to fully assess the credibility of potential cooperators and to screen any complications that could jeopardize a case at trial.

Attorneys on Thursday questioned whether Parnas' statements to date had conveyed the full extent of his involvement in the Ukraine scandal and his relationship with others involved in the pressure campaign and said he stood little chance of striking a deal with prosecutors.

"I think Lev Parnas cannot cooperate in the way SDNY prosecutors need him to, which is to come to Jesus about everything," said Kan Nawaday, a former Southern District prosecutor, who is now a partner with Venable in New York.

Michael Bachner, of Bachner and Weiner, said Bondy and Parnas had been "pretty overt" about their strategy, but noted that they were playing a risky game.

"It's a pretty unusual tactic because it means Parnas has to be willing to enter a guilty plea," Bachner said. "Parnas is in a way saying that he's willing to enter a plea in the Southern District case."

Bondy said Thursday that he was not giving up any of his defenses and planned to beat the charges in court.