CHARLESTON — Attorneys for former Massey Energy CEO Don Blankenship are seeking to erase his misdemeanor conviction related to the deadliest U.S. mine disaster in four decades. A former lead prosecutor called it a desperate act.

A motion filed Wednesday in U.S. District Court in Charleston claims federal prosecutors withheld information that would have assisted in Blankenship’s defense at his 2015 trial. It said the government produced reports and other information after the trial’s completion.

Blankenship, who has long maintained he didn’t get a fair trial, served one year in prison for a misdemeanor conviction related to the 2010 explosion that killed 29 men at the Upper Big Branch mine in southern West Virginia.

Blankenship assembled a new legal team for the latest court filing, which said evidence withheld by prosecutors until after trial “would have tipped the balance in Mr. Blankenship’s favor.”

The motion, which seeks an evidentiary hearing, was announced by Blankenship through his U.S. Senate campaign. He’s running as a Republican in the May 8 primary in West Virginia.

Deanna Eder, a spokeswoman for the U.S. attorney’s office in Charleston, declined to comment.

Former assistant U.S. attorney Steve Ruby, who was the lead prosecutor at the trial, said in an email to The Associated Press that the motion is “clearly a political Hail Mary. He’s three weeks from an election, and it sounds like he’s behind in the polls. If there were any merit to this whatsoever, he’d have filed it while he was still in prison instead of waiting almost until Election Day.”

Blankenship was convicted of a misdemeanor charge of conspiring to willfully violate safety standards.

According to the motion, Mark Clemens, who oversaw Massey’s production, sales and budgeting, said in an interview previously undisclosed by prosecutors that “there was pressure at Massey to run coal, but not enough pressure to overlook safety.”

The motion said many of the documents involved interviews with people who testified at the trial. Among them was Christopher Blanchard, who ran the Massey subsidiary that oversaw Upper Big Branch.

Blanchard testified under an immunity agreement with the government but helped the defense during almost five days of cross-examination. He previously told Blankenship’s attorneys that he himself didn’t break any laws and denied being involved in a conspiracy with Blankenship to violate safety regulations.

The motion said most of the previously undisclosed emails were written by former FBI Special Agent James Lafferty, who testified about a variety of investigation topics, from Blankenship’s compensation to his frequent receipt of reports detailing Upper Big Branch’s violations.

The documents also cited former Massey safety expert William Ross, who gave a tough review of the company’s safety shortcomings. While talking about a 2009 meeting with Blankenship, Ross testified he told Blankenship that Massey couldn’t “afford to have a disaster.”

Four investigations found worn and broken cutting equipment created a spark that ignited accumulations of coal dust and methane gas at Upper Big Branch. Broken and clogged water sprayers then allowed what should have been a minor flare-up to become an inferno.

During the trial, prosecutors called Blankenship a bullish micromanager who meddled in the smallest details of Upper Big Branch. They said Massey’s safety programs were just a facade — never backed by more money to hire additional miners or take more time on safety tasks.

Blankenship’s attorneys rested their case without calling a single witness on his behalf.