SPRINGFIELD, Ill. » A settlement in the workplace retaliation lawsuit against Democratic U.S. Rep. Tammy Duckworth is final and the plaintiffs can’t back out even if no paperwork was signed, the Illinois Attorney General’s office said today.

One of two women who sued Duckworth said Wednesday they wanted out of the agreement because they felt the congresswoman was tarnishing their reputations by still calling their allegations false. They said they also were upset that Duckworth’s campaign referred to their lawsuit as frivolous shortly after the agreement was announced last month.

The lawsuit has posed a potential obstacle in Duckworth’s campaign to unseat Republican U.S. Sen. Mark Kirk in a November race that could help determine which party controls the Senate. The congresswoman was scheduled to speak at the Democratic National Convention Thursday night.

The lawsuit alleges that Duckworth violated ethics laws in reprimanding Christine Butler and Denise Goins when Duckworth led the Illinois Department of Veterans Affairs. Butler told the Associated Press Wednesday that she and Goins never signed paperwork for the June 24 agreement, which stipulated that Duckworth did nothing wrong and included $26,000 for the plaintiffs’ attorney fees and court costs.

But a spokeswoman for the Attorney General’s office, which represented Duckworth, insisted Thursday that the agreement reached last month in Union County Circuit Court is final.

“We worked with a judge on June 24 and reached a final settlement. It’s typical practice that after finalizing a settlement, the parties sign our standard form. If a plaintiff declines to sign the form, that does not change whether the agreement is final,” spokeswoman Maura Possley said in an email.

The attorney general is Lisa Madigan, a Democrat whose father, Michael Madigan, is chairman of the state Democratic Party and speaker of the Illinois House.

Butler did not immediately return calls for comment Thursday. The attorney for her and Goins, Matthew Ferrell, did not respond to a message relayed to him by his office.

Randall Schmidt, a law professor at the University of Chicago, said the general rule is settlement agreements are enforceable even if they’re not put in writing.

“The fact that it’s not reduced to writing isn’t in and of itself enough to back out,” he said.

Schmidt said the exception to the rule happens when a “cooling off period” is required under law or when some terms to the agreement are left unresolved, like setting a reinstatement date for a wrongfully terminated employee.

The disagreement left some uncertainty about what will happen next in the case, and whether the judge will need to weigh in. Despite the settlement, an Aug. 15 trial date remains on the court docket.

In the lawsuit, Butler and Goins contend that Duckworth tried to fire one employee and gave another a bad review that cost her raises after the women complained about facility leadership at an Illinois VA home, where they still work.