HARRISBURG - State Rep. Leslie Acosta, who secretly pleaded guilty to a federal felony charge last year and stayed in office despite mounting calls for her to step down, is resigning.

Acosta, a Democrat representing sections of North Philadelphia, submitted her letter of resignation Friday to House Speaker Mike Turzai (R., Allegheny). In it, she said she would leave the legislature Jan. 3, the day lawmakers are to be sworn in for the start of a two-year legislative session.

Acosta did not state a reason for her decision, making only this plea in her letter: "Due to above average levels of constituent services in my district within my caucus, maintaining current staff levels is appreciated."

Neither Acosta nor her lawyer could be reached for comment.

Top Democrats, including Gov. Wolf and U.S. Rep. Robert Brady, had urged Acosta to resign since the Inquirer reported in September that she pleaded guilty in a sealed proceeding in March to one felony count of conspiracy to commit money laundering.

Several of Acosta's legislative colleagues also told her over the last few months that if she decided to remain in office, the House would block her from being seated when the new legislative session begins.

Acosta refused to step down, hanging on to her office and its $86,478 salary. She ran unopposed in the November election, winning a second two-year term.

House Minority Leader Frank Dermody (D., Allegheny) said Friday, "It's simply not tenable for her to attempt to continue her service into the next session, and that was repeatedly explained to her in recent months."

He added: "The people of this legislative district need a representative who is able to serve and engage fully in House business."

Her departure sets the stage for a special election.

As speaker, Turzai must call for a special election within 10 days of a vacancy. That election cannot be held until at least 60 days after the speaker calls for it, so the earliest it could occur is early to mid-March.

Brady, who chairs the Philadelphia Democratic City Committee, said he had spoken with two potential candidates for the special election, Noelia Diaz and Freddie Ramirez.

Brady said he would leave the decision on which candidate to select to the Democratic ward leaders who represent the 197th District.

"I don't get involved in it," he said.

He did say Diaz seemed to be winning more support among the ward leaders.

State Rep. Angel Cruz, a Democrat who leads the Seventh Ward, is supporting Diaz. His ward is just outside the 197th District, an area he represented in the House before redistricting moved the lines of his district.

Cruz was once a political ally of Acosta. Now he looks forward to her departure, scoffing at an interview she granted this month to the Spanish-language radio station El Zol.

In that interview, first reported on by Philadelphia Weekly, Acosta said Cruz should "show more respect" and stay out of efforts to select her replacement. Acosta also pushed for Ramirez to be selected.

"She's blaming me for all her faults," Cruz said Thursday. "I took her under my wing and I taught her."

Diaz, a marketing representative for a home health care agency, is a former volunteer for Acosta's political campaign. She has been active in efforts to run more women for public office and offered praise for Acosta despite her criminal case.

"No one can take this away from Leslie Acosta," Diaz said. "She's done things for our community. Unfortunately, this thing happened."

Ramirez, president of Pan American Mental Health Clinics, did not respond to requests for comment.

acouloumbis@phillynews.com 717-787-5934 @AngelasInk