Democratic U.S. Sen. Max Baucus, who is running for his sixth term next year, didn't own a home in Montana for 11 years of his 29-year Senate career.

State Republicans say Baucus has become a full-time Washington, D.C., politician who no longer really lives in Montana. They say the issue will come up in the upcoming campaign.

Baucus now owns one-half of his mother's Helena home, and Baucus and his wife, Wanda, are listed on the home's title as owners, records show.

Baucus spokesman Barrett Kaiser said the senator has always considered the house where he grew up "home" and returns at least twice a month.

"He's called it home for as long as he can remember," Kaiser said. "It's the house where his son comes to visit his grandmother and it's likely where Max's grandchildren will come, too."

Chris Wilcox, executive director of the Montana Republican Party, said it's wonderful that Baucus comes back to Montana to visit his mother, but said it's not the same thing as actually living here.

"The rest of our congressional delegation still keep their lives here, their families, their business operations" he said. "I think that's an important difference."

U.S. Sen. Jon Tester, a Democrat elected last year, and his wife Sharla rent an apartment in Washington, D.C., but have their house on the family farm near Big Sandy, said Matt McKenna, a Tester spokesman.

The Testers' daughter and son-in-law have taken over the farm and the senator and his wife have returned to the farm almost every weekend to help run the place.

Four-term Republican Rep. Denny Rehberg doesn't have an apartment at all in Washington. Instead, the congressman sleeps on the couch in his office, showers in the congressional gym and flies home to Billings every weekend where his wife and three children live.

Rehberg flies back to Washington on Monday morning, said his spokesman, Bridger Pierce.

Former Sen. Conrad Burns, a Republican who served 18 years in the Senate before losing to Tester last year, had condominiums in Arlington, Va., and Billings.

In contrast, Wilcox said, Baucus is "basically an absentee senator (who) occasionally comes to visit Montana."

Until 1991, Baucus owned a house in Missoula, where he practiced law for three years before running for Congress in 1974. He didn't own a home again in Montana until February of 2002, when be bought half of his mother's house from the Sieben Ranch Co., the family ranch started by Baucus' great-grandfather in 1897.

The ranch and Jean Baucus, the senator's mother, still own the other half, Kaiser said. The senator helps pay the utilities.

Baucus has also owned a home in Washington, D.C.'s Georgetown district since 1984.

He owns no other property in Montana, Kaiser said.

Kaiser said the senator didn't buy another house in Montana after selling his Missoula property because he always considered his mother's house home.

Baucus and his family have deep roots in Montana. The Sieben Ranch, a large spread north of Helena, is still in the family, now run by Baucus' brother, John Baucus. The family has lived in the area since the 1890s.

Baucus earned bachelor's and law degrees at Stanford University in Palo Alto, Calif. After graduating, he worked in Washington, D.C., as an attorney at the Civil Aeronautics Board and Securities and Exchange Commission.

Baucus returned to Montana in 1971 to practice law in Missoula. He served in the Montana House of Representatives in 1973 and 1974 and was elected to Congress in 1974.

Although Baucus didn't own a home in Montana for many years, it doesn't appear as though that made him ineligible to serve as a senator from the state.

The U.S. Constitution requires that senators, among other things, be an "inhabitant" of a state when elected. Black's Law Dictionary defines "inhabitant" as one who "resides actually and permanently in a given place and has his domicile there."

Rob Natelson, a constitutional law professor at the University of Montana, said there's more to having a "domicile" than simply having a home in a place. Generally speaking, Natelson said, "the rules of domicile require both having a residence and the intent to return to that residence, but there are exceptions."

One needn't own title to a place to have that as a residence, Natelson said. If Baucus actually spends his Montana time at a certain address, even if it was a place like his mother's home that Baucus himself did not own until 2002, that could qualify as a "domicile."

Furthermore, Natelson said, the constitution only requires senators to be an inhabitant of a state when elected. A person could have a Montana domicile on Election Day, give up that residence after election and establish a new Montana residence before the next election and satisfy the constitutional requirements for serving in the U.S. Senate.

State law is similarly hazy, said Janice Doggett, the chief lawyer in the Montana Secretary of State's Office, which oversees elections and election law.

The Montana Constitution says that citizens may vote and run in state elections if they are Montana residents. The first qualification of a Montana resident, according to state law is "where the individual's habitation is fixed and to which, whenever the individual is absent, the individual has the intention of returning."

Black's Law Dictionary defines "habitation" as a "dwelling place" or "abode."

Doggett said residency is "the union of act and intent." Baucus' work clearly calls him away from Montana, but if he has a place in the state he considers home and if he uses it as a home when he returns to the state, then he is a resident.

Doggett said it's perfectly acceptable for Baucus to use his mother's address as his own when registering to vote, as Baucus has done since at least 1994, county records show. Additionally, Baucus also pays Montana income and property taxes and licenses his car here, Kaiser said.

Kaiser said the senator tries to come back to Montana every weekend. He typically spends week-long congressional recesses at home, as well as the month-long August congressional break.

On top of his busy schedule, Baucus also values the time he can spend with his 90-year-old mother, whom Kaiser called "the single most important thing in (the senator's) life."

"Max has traveled more than 10,000 miles in Montana over the last six months alone," he said. "But when the work is done, all Max wants to do is come home to the house he grew up in, see (his mother) the most important person in his life and sleep in his own bed."