Rep. Harry Mitchell (D-Ariz.) is preparing for a battle beginning next week, after Republicans have chosen their nominee in the 5th district GOP primary.

Mitchell, a freshman representing a Republican-leaning, suburban Phoenix district, expects that presumptive Republican presidential nominee Sen. John McCain (Ariz.) could significantly boost his eventual GOP challenger.

But while some freshman Democrats running for re-election in solidly Republican districts chose to stay home and campaign rather than attend this week’s Democratic National Convention in Denver for fear of being branded a liberal or defined by the party’s presumptive presidential nominee, Sen. Barack Obama (Ill.), Mitchell had no qualms about attending.

“I think it’s a real tough race,” Mitchell said in an interview Tuesday morning while having breakfast with Arizona delegates. “I take [the race] very serious. Look at the [GOP] registration edge — I’m at a disadvantage. And if you look at the very fact that John McCain is from Arizona, there’s a lot” against me.

“But saying all that,” Mitchell continued, “I think that we’re in a very good position. We’re ready.”

Mitchell declined to say whether it would help or hurt his re-election campaign to have Obama campaign for him in his district.

“I don’t know if it would be good or bad,” Mitchell said. “I’m just going to run my campaign the best I know how.”

The National Republican Congressional Committee took issue with Mitchell’s confidence. NRCC spokesman Ken Spain said Mitchell is vulnerable because he is out of step with his district on key issues such as energy and immigration.

“Given Harry Mitchell’s full-throated opposition to drilling to lower the cost of gasoline and his vote to provide taxpayer-funded benefits to illegal immigrants, it is safe to say that he will be carrying some significant liabilities with him into the general election,” Spain said.

Republicans are expected to target Mitchell this fall, although exactly how much effort they will put into defeating him depends on the strength of their nominee, according to a GOP strategist with Arizona ties.

This strategist noted that the late Sept. 2 date of the Republican primary automatically puts the GOP nominee at a disadvantage.

The field in Tuesday’s GOP primary is six-deep, and Mitchell said that shows just how intent the Republicans are on ousting him this fall. Mitchell, the popular former mayor of Tempe, Ariz., who upended then-Rep. J.D. Hayworth (R) in 2006, noted that this is his 17th run for office.

Mitchell classifies himself as a moderate to conservative Democrat, saying he is confident of victory on Nov. 4 because he travels back to Arizona every weekend when Congress is in session, forging a connection with his constituents and working on the issues that matter to them.

Mitchell was at least confident enough in his prospects to attend the convention. Some of his fellow Democratic freshmen, including Reps. Steve Kagen (Wis.) and Christopher Carney (Pa.), chose to stay home and campaign rather than go to Denver.

But perhaps sensing the potential for political vulnerability, Mitchell also went out of his way to praise McCain. The Congressman said he has “a lot of respect” for the Republican presidential nominee, noting that he has known the Senator for many years.

“The district is interesting,” Mitchell said. “In the last election, the district voted for [Sen.] Jon Kyl [R-Ariz.] and also voted for me. So, hopefully the district looks at people as candidates and not just by the party, and that’s what I’m really counting on.”