Rep. John Shadegg, R-Ariz., said Thursday he will seek re-election after all, reversing his earlier decision to retire.

Shadegg had been egged on by more than 140 congressional colleagues, who signed a letter last week asking him to reconsider. He has his eye on the Senate seat of presumptive Republican presidential nominee John McCain, which will be open in 2010, and keeping his current job could make him a more attractive candidate.

In a news release announcing his about-face, Shadegg cited calls from constituents as his primary motivation.

“I expected my decision would elicit little reaction here in Arizona, and less in Washington. The events of the last week have, to say the least, stunned and deeply humbled me,” he said. “In the week following my announcement, thousands of people have contacted my office to encourage me to reconsider my decision. Dozens of old friends, some of whom I hadn’t spoken with in years, called my home urging me to reconsider.”

Shadegg’s decision to seek an eighth term reduces to 25 the number of House seats being left open by Republicans who are retiring or seeking other offices, and it is surely welcome at the National Republican Congressional Committee, which is charged with defending those districts.

Democratic tax attorney Bob Lord raised more than $600,000 last year in preparation for a run against Shadegg, and CQ Politics changed its rating of the race from “Republican Favored” to “Leans Republican” when Shadegg announced that he would retire.

The 3rd District has a strong Republican tilt, but Shadegg was held to 59 percent of the vote, his lowest share ever, in 2006.

Independent Annie Lloyd is running, as well.