It may well be that Democrat Mary Landrieu will sail clear of any actual legal jeopardy involving Republican challenges to her claim that yes, she’s a Louisiana resident, for the purposes of running for re-election to the U.S. Senate.

But the attacks could take their toll politically, especially as they continue the drumbeat of Republican political assaults that have kept Landrieu on the defensive.

“It’s certainly not an auspicious beginning to her re-election campaign,” Tulane University political science professor Brian Brox said.

That can only cheer Republicans — not just in Louisiana, but across the country. Their paramount objective in the fall elections is to wrest control of the U.S. Senate from the Democrats, which would give the Republicans a majority in both houses of Congress and allow them to put pressure on Democratic President Barack Obama.

Key to the Republican ambition is knocking off vulnerable Democratic incumbents in anti-Obama states, and Landrieu is at or near the top of their hit list. That makes any eruption in the U.S. Senate race in Louisiana big news, which is why the somewhat old story about Landrieu’s living arrangements recently attracted the attention of the national media. Professional Republican sympathizers have raised the noise level, with a deep-pocketed conservative political group producing a pointed online commercial keyed to the controversy.

“It’s been a successful tactic to keep her off balance, and keep her responding to challenges,” said Pearson Cross, chairman of the political science department at the University of Louisiana at Lafayette. “That’s not what she wants to talk about, obviously.”

Another thing she doesn’t want to talk about is her use of her official Senate office expense account to charter planes to campaign events, which violates federal law. She admitted last month to two such violations, which she attributed to bookkeeping errors, and paid back the taxpayer-provided money from campaign funds.

Republicans have made hay from “chartergate,” which also has drawn national media attention, and have pointed to more potential violations. The Louisiana Republican Party this week filed a formal complaint with the Senate Ethics Committee. Landrieu has withheld additional comment pending completion of an in-house review of all her flights in her 18 years in office, with the results of that review expected in the next few days.

What Landrieu, 58, does want to talk about is what she has done for Louisiana in her three terms in the Senate, and what she can do going forward as chairwoman of the Senate Energy and Natural Resources Committee, with its oversight of the oil and gas industry. Her relentless emphasis on Louisiana issues should help her fend off the latest Republican political assaults on her residency, Cross said, and so should her family name and her long-standing identification with the state: Her father was mayor of New Orleans, her brother is mayor now and she has held state and federal elective offices for nearly 35 years.

“To say that she’s not a Louisianian is really barking up the wrong tree, generally, for most people,” Cross said. “I just don’t think the argument has much bite.”

But what potentially makes things dicier for Landrieu is the current high level of antipathy toward Congress, Cross said. That sharpens the sting of a claim that she has “gone Washington,” and is a creature of the capital.

Accusations by challengers that incumbents have lost touch with their roots and with the folks back home are as old as the first election — or at least, the second election. Landrieu has faced them before in connection with her Washington residency: from Suzanne Haik Terrell, whom Landrieu defeated in 2002 to win her second term; and at least obliquely from John Kennedy, whom she beat in 2008 to win her third.

The latest challenge came initially from Rob Maness, a Republican and former Air Force colonel from Mandeville who is running with tea party support but without the backing of the Republican establishment, which favors U.S. Rep. Bill Cassidy, of Baton Rouge.

When Maness showed up in Baton Rouge late last month to file his documents to qualify as a Senate candidate, he handed in a letter to the Secretary of State’s Office questioning Landrieu’s own qualifications. Landrieu, he said, doesn’t live in Louisiana. His letter cited a newspaper article from 1997, the year Landrieu took office as senator, reporting that she was moving “permanently” to Washington (he left out the response by Landrieu, quoted in the article, when asked how she liked the city: “It’s not a friendly place like Louisiana,” she said). Maness also cited Landrieu’s use of her D.C. address when filling out various governmental forms.

One problem for Maness is that the Secretary of State’s Office was not the right place to file the challenge. By the time he lodged his complaint in the proper venue — the East Baton Rouge Parish District Attorney’s Office — DA Hillar Moore said it arrived too late for him to investigate and possibly pursue before a statutory deadline.

Another Republican, state Rep. Paul Hollis, of Covington, raised the issue in a state court lawsuit, which isn’t subject to the same deadline as a simple qualification challenge. Hollis was campaigning for the Senate earlier this year, but abandoned his effort and endorsed Cassidy.

But what state courts and parish prosecutors do or don’t do is moot, legal experts say. That’s because the U.S. Constitution spells out the requirements for senators, and states may not impose stricter ones. Even federal courts tend to defer to the Senate itself to determine if its members meet the standards.

Apart from age (at least 30) and citizenship (at least nine years), the Constitution says only that a senator must “when elected, be an Inhabitant of that State for which he shall be chosen.”

To begin with, “when elected” means just that: Election Day, which could be Nov. 4, when Landrieu, Maness, Cassidy and a few minor candidates appear of the ballot, or Dec. 6, when the two top finishers meet in a runoff election, should no one candidate capture a majority of the Nov. 4 vote. Any challenge before then is premature.

And should Landrieu win election, “There isn’t a chance in the world” that her Senate colleagues will deny her a seat, said Charlie Cook, of the national Cook Political Report in Washington. Other members of Congress with claims to residence as shaky as or shakier than Landrieu’s have survived challenges, he said.

U.S. Rep. Jim McCrery, a Republican who represented northwest Louisiana in the House from 1988 to 2009, faced a residency challenge after his 2004 re-election: Earlier that year, he had sold his home in Shreveport and moved with his wife and two sons to a house he bought in Northern Virginia. State and federal courts declined to intervene, and the U.S. House rejected the challenge.

When Landrieu was elected to her first six-year term as a senator in 1996, she and her husband, Frank Snellings, were the parents of a 4-year-old son, with a daughter on the way. The family rented a townhouse near the U.S. Capitol and built a four-bedroom home a few blocks away on East Capitol Street, Landrieu’s D.C. address now. In media accounts in 2001 and 2002, Landrieu said the decision to move her family to Washington was based on her wish to spend as much time as possible with her children.

Her Republican seatmate, David Vitter, rents an apartment in Washington near the Capitol and flies home between Senate roll calls to the house on Helios Street in Metairie where his wife, Wendy, lives with their three younger children (a fourth is away at college).

“Living here in Louisiana and being home whenever we don’t have votes has always given me a really good sense of what’s on Louisianians’ minds,” Vitter said in an emailed statement. “I think it makes a difference that I own my home here, my kids are in school here.”

Cassidy bought a condo in Washington to stay in when there on House business. His wife, Laura, lives with two of their three children in the family home near the LSU campus (the third child is away at college).

For her Louisiana residence, Landrieu lists the home on South Prieur Street in New Orleans in which she grew up and where her parents still live. She is a co-owner of the house and stays overnight there on visits to New Orleans, including in 2014, her campaign said.

The squabbling over where Landrieu lives is more political than legal, Cook said.

“It’s a symbolic thing,” he said. “Does this say something about where your heart and mind are?

“A lot of times it doesn’t hurt you, but sometimes it does.”

The residency issue was used effectively against Republican U.S. Sen. Richard Lugar, of Indiana, in 2012, when he lost in the Republican primary to a tea party challenger. Lugar, a six-term incumbent, had sold his house in Indiana and moved to the D.C. area when first elected in 1977; he was forced to repay nearly $15,000 in taxpayer funds — from a source similar to the money involved in Landrieu’s charter flights — that he spent improperly on hotel stays in Indiana over the years.

In this election year, Republican U.S. Sens. Thad Cochran, of Mississippi, and Pat Roberts, of Kansas, have confronted challenges over whether they actually live in the states they represent, and Tom Cotton, a Republican candidate for the Senate in Arkansas, has been criticized on similar grounds. Residency is an issue in the New Hampshire Senate election, too, with former Massachusetts U.S. Sen. Scott Brown switching his residency after his 2012 re-election defeat to his vacation home in New Hampshire before making his run there.

As for the impact of the issue in Louisiana, a deep-red state where polls show Landrieu struggling to reach the 50 percent she needs on Nov. 4 to avoid a head-to-head runoff with a sure-to-be lavishly funded Republican candidate?

“I don’t think it’s knowable,” Cook said. “But it’s a hit, it’s a real hit.

“I don’t think it’s devastating, or deal-breaking,” he said, “but every little thing that keeps her from getting to 50 on Nov. 4 hurts.”

Follow Gregory Roberts on Twitter, @GregRobertsDC. For more coverage of government and politics, follow The Advocate Politics Blog at politicsblog.