From right of radio dial, J.D. Hayworth challenges John McCain

PHOENIX — J.D. Hayworth is a large man, and to compensate for his indulgences, he hits the elliptical trainer every morning at 4, zipping along to an incongruous soundtrack of Elvis Costello, Frank Sinatra and old advertising jingles.

Until recently, he would then repair to a local radio station, where he would spend the better part of the day denouncing, in no particular order, illegal immigrants, all things Barack Obama, those who are insufficiently patriotic and, his favorite mark, one John McCain, the senior senator from Arizona.

Now, Hayworth, a former Republican congressman, is preparing to expand his political appetite for McCain by formally announcing on Monday what everyone in this state has known for months, his challenge to the senator in the Republican primary in August.

Hayworth hopes that by standing on the intersection of opportunity and timing, he can lure enough Tea Party sympathizers fresh off their convention in Nashville, Tenn., seducible independent voters (Arizona has an open primary) and conservative Republican grass-roots activists, who have long been disenchanted with McCain.

"The political winds of change are here," Hayworth said over lunch. "The conservatives are highly motivated and there is an intensity level among conservatives to take part in this primary. The atmospherics will help us."

Still bruised by his presidential run and struggling to find his footing in the fractured Republican Party, McCain remains a formidable force in his home state, through the sheer power of his name and fat campaign coffers. Most political analysts suggest Hayworth begins as the underdog, and McCain's supporters say they are confident.

"Sen. McCain takes every race seriously," said Brian Rogers, a spokesman for the senator's re-election campaign, "and is confident that the voters of Arizona will again return him to office as they have done in the past, and he is working hard to earn their continued support."

Yet McCain now finds himself jammed, moving starkly — and often awkwardly — to the right, apparently in an apparent to gain favor among the same voters whom Hayworth, a consistent voice for the far right, could pull toward him like taffy come summer.

McCain now sharply criticizes the bailout bill he voted for, pivoted from his earlier position that the Guantanamo Bay detention facility should be closed, offered only a muted response to the Supreme Court's decision undoing campaign finance laws and backed down from statements that gays in the military would be OK by him if the military brass were on board.