CHARLESTON, W.Va. (AP) — Attorneys for Don Blankenship say they have conducted a survey showing that the former Massey Energy CEO cannot get a fair trial in southern West Virginia, but prosecutors say he's short of warranting a move elsewhere.

The survey is a central piece of Blankenship's newly unsealed arguments that his criminal case needs to be heard in another court. His attorneys have suggested Martinsburg or Baltimore.

On Thursday, U.S. District Judge Irene Berger delayed the former coal executive's trial date to July 13, allowing more time for those discussions and others.

Would-be jurors have been swayed by extensive news coverage and attempts to paint Blankenship the "bogeyman" in policy debates and political campaign ads, Blankenship's attorneys argue.

Blankenship was charged with conspiring to violate safety standards, among other violations, related to Upper Big Branch Mine in Montcoal, West Virginia. An explosion at the mine killed 29 men in 2010, the deadliest U.S. mine disaster in four decades.

"Any juror chosen from this community would be sensitive to the importance that much of the community attaches to a conviction of Mr. Blankenship, and would be aware that important aspects of this case have already been tried in the press," Blankenship's attorneys wrote in a motion to change the venue.

In a memorandum filed in federal court, Blankenship's attorneys say the results of their "reliable survey" show that about half of the potential jurors in the Beckley Division already believe Blankenship is guilty.

The memo was made publicly available Wednesday after the AP and other media challenged its sealing. Previously, a federal appeals court struck down a restrictive gag order in the case after the same media groups challenged it.

In surveys of the Martinsburg and Baltimore areas, the memo says, people were much less familiar with Blankenship and the mine disaster, and were less inclined to consider him guilty ahead of the trial.

Prosecutors say even if Blankenship's survey is accurate, there are examples of other high-profile cases not being moved. They cited the Enron Corporation's CEO, whose case stayed in Houston despite plenty of pretrial press coverage in a community that was deeply affected.

Moving the case without even trying to field a fair jury in southern West Virginia would be inappropriate, prosecutors wrote.

Prosecutors favor Charleston or Huntington if they have to relocate, though Blankenship contends his survey shows about half of Charleston respondents also think he's guilty.

Berger, the judge, has already discarded several of Blankenship's motions to drop the case, including one that said the government targeted him in a selective and vindictive way.

After the 2010 explosion, four investigations found that worn and broken cutting equipment created a spark that ignited accumulations of coal dust and methane gas. Broken and clogged water sprayers then allowed what should have been a minor flare-up to become an inferno.