JONESBORO, Ill. >> A civil lawsuit alleging ethics violations nearly a decade ago has become an issue in a Democratic congresswoman’s bid to unseat first-term Republican U.S. Sen. Mark Kirk in what is expected to be one of the most competitive 2016 Senate races.

The complaint alleging workplace retaliation was filed in 2008 by two employees of a southern Illinois veterans’ home against Tammy Duckworth, a Chicago area congresswoman who at the time led the Illinois Department of Veterans Affairs; and Patricia Simms, the home’s acting administrator in 2006 and 2007.

A federal judge dismissed the suit as a “garden variety workplace case.” It was refiled in state court and dismissed again, but then narrowed and brought back a third time. A routine status hearing was held Tuesday, with a trial date tentatively set for next April, a month after the Senate primaries.

Illinois Republicans have highlighted the case, seeking to thwart Duckworth’s bid against Kirk, a moderate in a Democratic-leaning state who is considered one of the most vulnerable Republican senators. Kirk, who suffered a stroke in 2012 and has been criticized for a string of public gaffes, can expect a tough re-election challenge in a presidential year, especially if Illinois-born Hillary Rodham Clinton is on the ballot. Democrats need to make a net gain of at least four seats in 2016 to take back the Senate majority won by Republicans last year.

The Republicans portray the lawsuit as a “whistleblower” case against Duckworth, who grew up in Hawaii and attended McKinley High School and the University of Hawaii. The congresswoman denies treating the employees unfairly. The state Attorney General’s Office is handling Duckworth’s defense. In April, the state asked to have the suit dismissed after waiting more than three years for Duckworth’s accusers to provide requested documents.

Christine Butler, a 21-year state employee, accuses Duckworth in the lawsuit of firing her for insubordination over complaints about Simms. Butler’s termination was reversed by Duckworth within days.

Denise Goins, a human resources secretary, alleges that her complaints about Simms were also ignored and led to an unfavorable performance review that prevented her from receiving a raise. Goins says Duckworth urged her to “do your job and keep your mouth shut.”

The two state workers are seeking compensatory damages of at least $50,000, as well as other financial penalties.

Duckworth, an Iraq War veteran who led the state agency from December 2006 until early 2009 before joining the federal Department of Veterans Affairs, deflected the allegations when she defeated an incumbent Republican for the state’s Eighth Congressional District seat in 2012.

But the state Republican Party continues to hammer her on the issue.

“Rep. Duckworth has continuously refused to explain her actions,” said Kirk campaign manager Kevin Artl. “It is our hope that the legal system will deliver what she has not — the truth about her actions and justice to the whistleblowers.”

The state Republican Party also points to an email it received under Illinois public records laws in which Duckworth acknowledged that she “screwed up” by not first placing Butler on leave with pay.

Leaders of Duckworth’s campaign declined comment, citing the pending legal dispute. But Matt McGrath, an Illinois Democratic Party spokesman, said Kirk’s supporters are exaggerating what he termed a workplace disagreement. He called the GOP focus on the suit “the politics of desperation.”

Simms’ attorney, Joe Bleyer, said the two state workers are scheduled to give depositions this month.