Michael Cohen’s effort to enlist House Democrats in his efforts to stay out of jail were rebuffed Monday.

Rep. Adam B. Schiff, California Democrat and chairman of the House intelligence committee, said his panel would not get involved with the sentencing of President Trump’s longtime personal attorney and fixer.

Cohen’s legal team had sent a letter last week saying he may have more information helpful to the panel’s efforts to investigate Mr. Trump based on a newly found hard drive. But he said he could only provide that help if he stayed out of jail.

On Monday, Mr. Schiff said no dice.

“I don’t get involved in sentencing matters as a practice,” he told CNN when asked about Cohen’s letter. “I never have in Congress and that’s been my policy.”

Cohen is set to report to prison May 6 to start serving a three-year sentence for campaign-finance, perjury and other crimes not directly related to the 2016 election and purported collusion between the Trump campaign and the Kremlin.

Despite refusing Cohen’s efforts to have Congress act as a character witness to federal prosecutors, Mr. Schiff he would still be interested in whatever Cohen might have, whether he is free or locked up.

“We continue to encourage Mr. Cohen to provide us any materials that he has that are relevant to our investigation,” he said. “We will continue to do so and hope that he has additional information to offer.”