NEW ORLEANS (AP) — Former challenger Paul Hollis has sued Democratic U.S. Sen. Mary Landrieu, contending that she cannot represent Louisiana because she lives full-time in Washington.

Under U.S. law, only “an inhabitant” of a state can be elected to the U.S. Senate to represent the state.

“Mary L. Landrieu is in reality a full-time permanent inhabitant of the District of Columbia. … (B)y all measurable and legal standards, her actual domicile is her 2.5 million dollar residence on Capitol Hill, the only home she owns,” Hollis, a Republican state representative from St. Tammany Parish, said in a lawsuit filed Friday in state district court in Baton Rouge.

Landrieu is registered to vote in Louisiana, using the New Orleans address where her parents live. The house is owned by a trust in which the senator, her eight siblings and their parents share equally.

“I have lived at my home on Prieur Street most of my life and I live there now, when not fulfilling my duties in Washington or serving constituents across the state,” Landrieu said in a statement that echoed one sent to The Associated Press last week.

Hollis dropped out of the race in July and endorsed Republican U.S. Rep. Bill Cassidy.

He said he sued because “I think it’s important.”

Cassidy and tea party favorite Rob Maness have both taken aim at Landrieu’s residency in speeches.

“Senator Landrieu’s physical address is in Washington, D.C. but more importantly, she votes like a D.C. resident” on matters such as the Affordable Health Care Act, Cassidy spokesman John Cummins said in an email.

Residency criticism in 2002 and 2008 failed to unseat Landrieu, whose family has strong New Orleans roots — her brother Mitch is in his second term as mayor, a job once held by their father, Moon.

Maness also sent information about Landrieu’s residency to four district attorneys.

There was no word on whether any of them plans to act.

“It was Rob’s hope that a citizen legal action wouldn’t be necessary to compel the proper authorities to uphold the law,” wrote Kurt Bardella, a Maness campaign strategist.

“However,” he wrote, “in the absence of that action, it is important that every avenue is pursued to ensure the integrity of our election process.”