Louisiana Sen. Mary Landrieu, in a tough re-election bid, is facing mounting legal challenges to her residency status, including a lawsuit filed this weekend by a former Republican challenger.

The suit filed by GOP state Rep. Paul Hollis, who exited the Senate race in July, contends that Landrieu, a Democrat, cannot represent Louisiana because she lives full-time in Washington.

He argues that federal law says 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 residence on Capitol Hill, the only home she owns," Hollis said in the lawsuit filed Friday in state district court in Baton Rouge.

The suit was filed the same day that Rob Maness, a Republican and Tea Party favorite still in the November race, called on four Louisiana district attorneys to object to Landrieu’s residency qualifications.

"The Constitution, Louisiana law and common sense says candidates for Senate have to live here when they qualify,” Maness said Friday. “All of the evidence shows that Mary Landrieu doesn't live here."

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 has told Fox News and The Associated Press.

Hollis, who now endorses Rep. Bill Cassidy in the GOP effort to unseat Landrieu and win control of the Senate, said he sued her because "I think it's important."

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

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.

Whether Hollis or Maness’ arguments will result in any consequences for the 58-year-old Landrieu remains to be seen.

However, their efforts will likely help Republicans trying to portray Landrieu as a creature of Washington and connect her to fellow Democrat President Obama, who now has low approval ratings.

Republicans have since the start of the 2014 election cycle targeted Landrieu in their effort to win a net total of six Senate seats and take control of the upper chamber.

Landrieu has held tough, despite the attacks, well-funded political action committees against her and running for office in a conservative state.

She is tied with Cassidy, her closest Republican challenger, according to essentially every poll.

However, the late-coming attacks could impact the outcome of the race considering the November elections in Louisiana are open primaries, which means the winner must get 50 percent of the vote or face a runoff.

The Associated Press contributed to this report.