PHOENIX — Sen. John McCain will end his presidential campaign today in the state where he has been a favorite son since he was first elected to Congress in 1982.

If the campaign of Sen. Barack Obama has its way, though, McCain may not feel so comfortable here in his home state tonight. Obama’s campaign hopes to put Arizona in play as part of a wider effort to challenge McCain in states that President George W. Bush ’68 carried in the past two presidential elections.

For his part, McCain began his Tuesday at midnight, with a rally on the steps of the courthouse in Prescott, the small Arizona city where Barry Goldwater started and ended his bid for the presidency in 1964 and where McCain has finished each of his four Senate campaigns.

From there, according to information released by his campaign, the Republican candidate will get a few hours of sleep followed by a brief rally at an airport hangar in Grand Junction, Colo. He will spend the rest of the day in the West, finishing the day here in the Valley to vote and watch the election returns.

Obama has not visited McCain’s home state recently, but his campaign has bought ad time here over the last week as polls have shown a tightening race. The liberal organization also purchased ad time in Arizona; its 30-second spot shows a military veteran who says, “I am a lifelong Republican, and I’m voting for Barack Obama.”

In a letter to supporters, Obama’s national field director, Jon Carson, tried to rally the support of Arizonians longing for change.

“[McCain] should have a comfortable lead with voters who’ve known him for nearly three decades,” Carson wrote. “That says all you need to know about the strength of Barack’s message and the grassroots movement we’ve built.”

Obama’s surrogates have pointed repeatedly to an article in the Arizona Republic last week that called the race “neck and neck” and said McCain was “struggling in his own backyard.”

The article cited a poll by researchers at Arizona State University that showed McCain leading Obama by only two percentage points — 46 to 44. A more recent poll by the polling firm Research 2000 shows an even tighter race, with McCain leading 48 to 47. But four other polls conducted in the state over the last week put McCain ahead by four, five or as many seven percentage points.

Ironically, it was the same Arizona Republic, the newspaper in Arizona with the highest circulation, which prominently endorsed McCain in late October.

“Nowhere else in the country do voters know John McCain like Arizonans know John McCain,” the editorial board wrote.

Tonight, the nation will find out where Arizona stands on one of her own.