TOLLESON, Ariz. — Gary Godsey liked all that “Straight Talk Express” stuff from Senator McCain’s 2000 presidential campaign, liked that he seemed to make up his own mind on issues and not bend with the poll-driven winds. But these days, Mr. Godsey is less sure.

The same straight-talking, nononsense traits that Mr. Godsey once admired in the Vietnam War hero have morphed, in his mind, into intransigence. It’s a fine line, Mr. Godsey acknowledges, but a line nonetheless, and it is evidence of how Mr. McCain’s national political troubles have begun seeping into his support at home in Arizona’s parched landscape.

“I think he’s losing who he really is,” said Mr. Godsey, 64, who retired four years ago and moved from San Diego to a new subdivision just outside Phoenix. Mr. Godsey voted to re-elect Mr. McCain to the U.S. Senate in 2004.

“He doesn’t come across like he used to. He’s too much like a control freak: ‘My way is the right way.’ He’s not going to bend,” Mr. Godsey said last week as he tucked away groceries in his tract house at the edge of the desert.

Although no one is ready to declare Mr. McCain vulnerable here in Arizona — he won 76.7% of the vote in 2004 and doesn’t face reelection until 2010 — for the first time in a long time analysts and other political watchers say they see signs of weakness.

The cause: the same gravitational forces weighing down Mr. McCain nationally. The war in Iraq is just as unpopular here as elsewhere, and it has cost Mr. McCain support among independents, Arizona’s fastest-growing block of voters.

At the same time, Mr. McCain’s immigration reform proposal has alienated Arizona conservatives, who believe the senator supports amnesty for undocumented immigrants in America — a top issue here, where every year more than 100 people die trying to sneak in from Mexico across Arizona’s deserts.

“It’s kind of like the dike is broken,” said Earl de Berg, a Phoenix pollster and analyst. “He was the most well-regarded politician in Arizona for a long time because of his national image. But some people who were not really all that enthusiastic are beginning to cut loose. … Anti-immigration people are going so far as to call him a traitor. That’s pretty tough language to level against a war hero.” So far, Mr. de Berg said, the slippage is measured only in anecdotes and an increase in critical letters to the editor in local papers. He plans to poll Arizonans next month on Mr. McCain, including hypothetical election match-ups with state political figures such as popular Governor Napolitano, a Democrat whom both parties credit with turning around the state’s economy (she won re-election in 2006 over token opposition with 62% of the vote).

Local Republicans’ willingness to look elsewhere can be counted in dollars. McCain’s presidential campaign has raised nearly $1.9 million from fellow Arizonans, more than all the other Republican candidates combined. Yet a former Massachusetts governor, Mitt Romney, has raised just more than $1 million here.

A growing ambivalence about Mr. McCain emerged in conversations with Arizona voters last week. Many loyalists, such as Army veteran Paul Wilson, 43, think that if Mr. McCain is forced out of the presidential race, he would still win re-election to his Senate seat.

“As a senator, he’s not necessarily affected by how he is doing (in the presidential race),” Mr. Wilson said as he stretched before a 2.4-mile hike, 1,264-feet up Camelback Mountain. “I would like to think that he’d win.”

Other people who once supported Mr. McCain, though, have drifted away.

“I just e-mailed him to tell him how disappointed I am in his immigration policy,” said Tracy Farrell, 48, a Republican who voted for Mr. McCain in 2004 but said she could not foresee voting for him again. “Clearly, he’s not listening. … I don’t think he represents his constituency.”

Ms. Farrell, a kindergarten teacher, says the rawness of emotions over the war and immigration reform also have brought Mr. McCain’s occasionally prickly personality to the fore.

“I admire a person who sticks to principals, but you have an obligation, when you set out ideals, to communicate those,” Ms. Farrell said as she ate lunch on the patio beneath a water-mister, a vain attempt to escape the 115-degree midday heat at Phoenix’s Esplanade shopping complex. “He has never articulated why he is for the immigration reforms. He just says, ‘Because that’s the way it is.’ He’s defensive rather than explaining.”

The break with voters like Ms. Farrell illuminates how Mr. McCain has cornered himself. His political persona is defined by the perception that he is a man of resolute positions.

Yet polls have shown that the electorate — which initially supported the war in Iraq and is now against it — changes its mind on issues. A candidate who changes positions, however, invites accusations of flip-flopping for political gain.

Mr. McCain faces the added pressure of being two political figures at once: a local politician holding a Senate seat and a player on the national stage. And in a state whose population has nearly doubled since Mr. McCain won his first Senate election in 1986, Mr. McCain is becoming known more in Arizona by his national reputation.

As his political star falls nationally, it could further erode confidence in him at home.

Voters “carry in with them a national understanding of who he is,” said Phoenix Democratic strategist Rick DeGraw. “He’s going to be the only political name they know, and it’s not like the vast majority of voters do in-depth research on what these folks stand for.”