A Louisiana judge on Friday dismissed a lawsuit challenging the residency of U.S. Senator Mary Landrieu, a Louisiana Democrat in the midst of a close reelection campaign.

Landrieu has faced criticism by Republican challengers for listing her parents' house in New Orleans as her home address in election filings.

In dismissing a lawsuit questioning her qualifications to run, District Court Judge Wilson Fields said the challenge was premature before the election, according to local media reports.

The case was brought by a Republican state legislator, Paul Hollis, who had been among Landrieu's challengers but has dropped out of the race.

A three-term incumbent, Landrieu is considered among the most vulnerable Democrats in the partisan battle for control of the U.S. Senate.

"The judge was clear - Senator Landrieu resides in Louisiana and is qualified to run for the Senate, as she has three times in the past," Fabien Levy, communications director for the Landrieu campaign, said in a statement.

The senator shares a house in Washington with her husband but has maintained that her parents' home, where she grew up, remains her primary Louisiana residence.

She will compete against U.S. Representative Bill Cassidy of the Baton Rouge area and Tea Party-backed challenger Rob Maness, both Republicans, in a November 4 open primary. Under state election rules, if no candidate gains a majority in the open primary, the top two candidates will meet in a December runoff.