Flake, 45, was once considered a one-issue candidate focusing on attacking the spending policies of the GOP side of the House of Representatives. He is now beginning to look more like a maverick in the mode of his close ally, Sen. John McCain, R-Ariz., and is becoming a strong bet to replace him should McCain decide to retire after 2010, The Arizona Republic reported Tuesday.

In the past, Flake has annoyed his own party by constantly blowing the whistle on what he considered dubious spending projects and by refusing to pursue pork for his own constituents. But now he is also being seen as a possible successor for Arizona's other Republican U.S. senator, John Kyl, or even as a gubernatorial choice, observers said.

"He embodies what a lot of people are looking for in Republican leadership right now," Jaime Molera, a Kyl consultant, told the Republic. "Here's a guy who is incredibly intelligent, who brings a strong vision of a real conservative and who is just very charismatic."