WASHINGTON (CNN) — Rep. Rick Renzi, an Arizona Republican first elected in 2002, will retire when the 110th Congress comes to a close in 2008.

“I will not be seeking re-election to the U.S. House of Representatives in 2008,” Renzi said in a prepared statement. “I am honored and thankful to serve Arizona’s first district and appreciate all that we have accomplished together over the past 6 years.”

Renzi is the fifth Republican in recent months to announce plans to leave Congress. Ohio Rep. Deborah Pryce, Illinois Rep. Ray LaHood, Mississippi Rep. Chip Pickering and Illinois Rep. Dennis Hastert have also said they will not seek reelection. Hastert served as House speaker before Democrats took back control of the House in 2006.

Oklahoma Rep. Tom Cole, who chairs the National Republican Congressional Committee, said it will be one of his top priorities to keep this Arizona seat in GOP hands.

“Arizona’s First Congressional District is a Republican seat and we have every intention of keeping it that way,” Cole said in a prepared statement.

Renzi has been under an ethical cloud ever since a family business was raided earlier this year by the FBI, which is investigating whether he used his federal office for personal gain. Renzi has never admitted to wrongdoing.

Democrats immediately jumped on the news and sought to tie Renzi with two of his former GOP colleagues who are now serving time in federal prison for misusing their congressional offices.

“Rick Renzi is following the Republican Conference corruption playbook – both Bob Ney and Duke Cunningham announced they were ‘retiring’ before they pleaded guilty and resigned,” Jennifer Crider, spokeswoman for the Democratic Congressional Campaign Committee, said in a statement. “The people of Arizona’s First Congressional District deserve to be represented by someone who puts them first and is free of criminal and ethical scandal.”

– CNN Political Editor Mark Preston