Former Rep. John Shadegg (R) won't run for Sen. Jon Kyl's (R-Ariz.) seat.

Kyl announced Thursday he won't seek reelection in 2012. His announcement touched off speculation that Shadegg, who retired last year, would seek a return to public office.

In a statement, Shadegg said he was encouraged to run but is going to "pursue other opportunities."

"Now is not the right time, either for me or my family, to pursue the opportunity created by Senator Kyl's decision," he said in a statement Friday. "While it has been a tremendous privilege to serve the people of Arizona in the U.S. Congress, I will not be a candidate for the Senate in 2012."

Shadegg's decision will likely do little to thin out what's expected to be a crowded GOP field. GOP insiders have pegged Rep. Jeff Flake (Ariz.) as early front-runner.

Other possible contenders include Rep. Trent Franks (Ariz.) and former Rep. J.D. Hayworth (Ariz.). Hayworth told The Hill on Thursday that he's weighing a run. Other potential candidates, according to Republicans, are Maricopa County Sheriff Joe Arpaio, former state Treasurer Dean Martin and state Senate President Russell Pearce.