LITTLE ROCK — State Treasurer Martha Shoffner resigned Tuesday, a day after appearing in federal court to face an extortion charge.

In a letter to Gov. Mike Beebe, Shoffner said she tendered her resignation "with great sadness."

"I am proud to have been elected by and to have served the people of the state of Arkansas and regret that I can no longer perform the duties and responsibilities owed to the public," she said in the letter.

She said her resignation was effective at 5 p.m. Tuesday. Her letter made no mention of the charge she faces.

Shoffner, became the first state constitutional officer to resign under pressure from office since former Gov. Jim Guy Tucker, a fellow Democrat, stepped down in July 1996 following his conviction on federal charges in the Whitewater investigation of Bill and Hillary Clinton’s business dealings in Arkansas.

The two-term state treasurer had been under FBI investigation for more than a year because of financial dealings in her office before agents arrested her at her home Saturday in Newport. In a criminal complaint filed Monday, federal authorities accused her of taking kickbacks for directing state bond business to a single broker.

Beebe spokesman Matt DeCample said Tuesday evening that the governor plans to appoint a new state treasurer "as soon as possible."

"Obviously (the governor) is glad she took this action relative quickly," DeCample said, adding that Beebe has indicated he has some possible candidates for the constitutional office in mind but did not want to discuss it with them until Shoffner officially stepped down.

DeCample declined to say who the governor was considering. The new treasurer will be barred from seeking the office in 2014.

Calls for Shoffner’s resignation, from fellow Democrats and Republicans alike, had been mounting since before her appearance in U.S. District Court on Monday. Both the Republican and Democratic House leaders Tuesday called for Shoffner to resign and for Beebe to call a special legislative session to remove her from office if she refused.

Beebe said earlier Tuesday he would consider calling legislators into special session to remove the embattled state treasurer but wanted to give her a chance to step down on her own.

Shoffner, 68, is accused of taking at least $36,000 in kickbacks, delivered covertly in a pie box, for directing the bulk of bond transactions made by her office to a single broker, according to federal authorities. After a hearing in federal court Monday, she was released on her own recognizance but ordered to surrender her passport. A federal grand jury will decide whether to indict her.