Gabrielle GiffordsJanet NapolitanoJeff FlakeJohn KylJohn Shadegg

AZ-Sen: Senator John Kyl to Retire – Seat Downgraded to Leans Republican

Arizona Republican Senator John Kyl

At 68 years old, Arizona U.S. Senator John Kyl is calling it quits.

Three-term Sen. Jon Kyl will announce his retirement at a noon ET news conference Thursday in Phoenix, two Republican sources confirmed to Fox News.

The Arizona lawmaker, the No. 2 Republican in the Senate, will be the fifth senator scheduled for re-election next year to announce a departure from Congress in 2012.

Kyl, 68, served four terms in the House before winning a Senate seat. In 2006, he was named one of the 10 best senators by Time Magazine.

“He’s leaving now at the top of his game, he has money in the bank, and he’s one of the few long-term incumbents who doesn’t face a Tea Party challenge,” a senior Senate GOP aide with knowledge of Kyl’s decision said.

Kyl has never lost an election, and would not have been expected to lose a vote for a fourth term. He will be 70 years old when he leaves.

Good for Kyl as he leaves with enough years to enjoy life and leaves at the top.

For Republicans, this may not be so good as this seat would be an easy hold for them. In fact, Larry Sabato has downgraded GOP prospects to “Leans Republican.”

So, who are mentioned as possible replacements?

Republicans: Rep. Jeff Flake, former Rep. John Shadegg and probably countless others in the Arizona Legislature

Democrats: Former Arizona Governor and Homeland Security Chief Janet Napolitano and Rep Gabrielle Giffords (if she rehabs in time).