SEDONA, Ariz. — John McCain looks to formally nail down the Republican presidential nomination this week, though he is already into one fall campaign mode: Fending off opposition attacks.

The Arizona senator's campaign is busy fielding questions over his decision to pull out of the public financing system, his support of the Iraq war, lobbyists working in his campaign, an endorsement from a controversial evangelical, and even his place of birth.

It's not defense, said McCain press secretary Brooke Buchanan. Instead, the campaign is moving ahead in the face of "mischaracterizations" of "issues that are so in the weeds."

"We are not going to let the Democrats define us," she said. "We are going to define ourselves."

Democrats have eight months to offer their view of McCain and will take every chance to do so, says Damien LaVera, a spokesman for the Democratic National Committee.

"We're trying to point out the man behind the myth," LaVera said. "John McCain is just another Washington insider who thinks the reforms he champions apply to everybody but himself."

McCain didn't campaign Sunday, instead hosting a barbecue for staff members, supporters and reporters at his home in the Arizona mountains. He plans to spend the next two days in Texas, one of four states holding primaries Tuesday.

McCain enters the week with 1,014 delegates, according to The Associated Press, only 177 short of the majority needed to clinch the GOP nomination. There are 265 delegates available Tuesday in Texas, Ohio, Rhode Island, and Vermont.

Although Republican opponents Mike Huckabee and Ron Paul remain in the race, McCain is starting to take most of his fire from Democrats on topics that include:

— Public finance. McCain reversed field last month, announcing he would forgo public financing for the primary season and the spending limits that accompany it.

The DNC has filed a complaint with the Federal Election Commission to block McCain's spending plans, saying he can't opt out because his campaign used the promise of federal money to secure a loan. McCain attorney Trevor Potter said the campaign put up its assets as collateral and can withdraw from the system because it never received a public check.

— Iraq. Sens. Barack Obama and Hillary Rodham Clinton have criticized McCain for suggesting that the United States could be in Iraq for "another 100 years." McCain says the comment has been misinterpreted.

— Lobbyists. Obama has criticized McCain for using current and former lobbyists in his campaign, references to senior adviser Charles Black and campaign manager Rick Davis.

Lobbyists, McCain said, have never influenced his actions in Congress, and the aides in question are "honorable people."