Rep. John Shadegg, R-Ariz., said Monday he will not be seeking re-election.

"I have no intention of letting up in the fight for my beliefs," Shadegg said in an e-mail. "I simply believe it is time for me to do so in some other capacity."

Shadegg, a seven-term Republican, becomes the 29th House Republican in the past 13 months to either leave or decline to seek re-election at the end of this term.

Shadegg, 58, said he believes a Republican will win his seat in November.

He is best known for his unsuccessful challenge to House Republican leader John Boehner, R-Ohio, and Minority Whip Roy Blunt, R-Mo., for the top GOP position after Texas Rep. Tom DeLay's resignation.

"He was a smart, honest and honorable rival during the race to be Republican majority leader in 2006, and has continued to be a valued part of our Republican team since," Boehner said. "I will be sorry to see him go."

The Arizona congressman said he is in good health, and raised more than $1 million last year that could be used to defend his seat in the November elections.

"The bottom line is that this is a personal decision between my family and me, about our dreams, goals and ambitions," Shadegg said. "We have concluded that it is time for me to seek a new challenge in a different venue to advance the cause of freedom."

Shadegg last month returned $10,000 in political donations that have been called into question. The Arizona Democratic Party had filed a complaint with the Federal Election Commission alleging that Shadegg used his political action committee to skirt campaign finance laws that limit individual donations.

Shadegg said he was returning the money "to remain above reproach in the handling of my campaign finances and to dispel even the potential appearance of improper conduct relating to these funds."