Julius Henson, a political operative who worked for former Maryland governor Robert L. Ehrlich Jr. (R), took responsibility Friday for an anonymous election-night robocall in the state that suggested Democratic voters “relax” and stay home even though polls still were open.

Henson told reporters in Baltimore that Ehrlich, who lost Tuesday to Gov. Martin O’Malley (D), probably did not know about the call, which went to more than 50,000 voters. A spokesman for Ehrlich declined to comment.

Henson characterized the call as “counterintuitive,” saying it actually was meant to inspire Ehrlich supporters to vote rather than keep O’Malley supporters home.

“The call was designed to have people who would have gone to vote for Bob Ehrlich to go out and vote for him,” said Henson, a longtime Democratic operative hired this year by Ehrlich.

Democrats on Friday stepped up their criticism of the episode – which now has prompted multiple investigations – saying it clearly was intended to suppress voter turnout in Baltimore and Prince George’s County, two heavily Democratic, predominantly African American jurisdictions.

A woman’s voice on the call told voters that O’Malley had been “successful,” adding: “Our goals have been met. . . . We’re okay. Relax. Everything is fine. The only thing left is to watch it on TV tonight.”

Aides to O’Malley said they started receiving complaints about the call on Tuesday about 6 p.m., two hours before the polls closed.

The involvement of Henson first _blankwas reported Friday on the Web site of the Baltimore Sun. The Sun reported that the call was ordered by Rhonda Russell – an employee of Henson’s political consulting firm, _blankUniversal Elections – and facilitated by the Pennsylvania-based company _blankRobodial.org.

Russell did not return phone calls Friday.

“I don’t know what possessed her to do it, but it happened,” Mark Hampton, owner of the robocall company, told The Post.

Hampton said he had been contacted by the Office of the Maryland State Prosecutor, whose jurisdiction includes election-law violations.

Raquel Guillory, a spokeswoman for the Maryland attorney general’s office, said it also is investigating whether the calls violated laws related to fraud and voter suppression. She said automated calls are required by law to disclose who is responsible for the content. The robocall in question did not.

Sen. Benjamin L. Cardin (D-Md.) has asked U.S. Attorney General Eric H. Holder Jr. to look into the episode.

Maryland Democratic Party Chairwoman Susan Turnbull said she considers the robocall “shameful.”

“We hope the Ehrlich campaign will fully disclose their role in this unfortunate episode and cooperate fully with any ongoing investigations in the matter,” Turnbull said. “The right to vote is precious in a democracy, and anyone who attempts to deny that right to citizens should be prosecuted to the full extent of the law.”

Ehrlich previously told reporters that Henson was retained for advice on reaching out to the African American community. Ehrlich’s campaign has paid two consulting firms run by Henson more than $97,000 this year, according to finance reports.

On election night, Ehrlich spokesman Andy Barth said his campaign had nothing to do with the robocall and did not know who was responsible. “We condemn the calls,” he said at the time.

Hampton said Russell used an automated process to place the robocall through an account she had maintained with the company for some time. The process allows account holders to phone in messages that are sent out to phone numbers they provide.

Hampton said no one at his company heard the message before it was distributed.

“We’ve had a few candidates who’ve tried to pull the same kind of stunt before,” he said. “If they ask us to set it up, we don’t do it. We certainly don’t condone voter suppression.”

Ehrlich also was linked to a 2006 episode that Democrats characterized as a dirty trick. On Election Day, a group of low-income men were bused in from Philadelphia to hand out fliers at polls in largely black precincts. The fliers made it appear Ehrlich was a Democrat. Ehrlich’s wife, Kendel, greeted some of the men that morning.