Washington, D.C. ? Nebraska Sen. Chuck Hagel, a persistent Republican critic of the Iraq war, intends to announce Monday he will not seek a third term, according to Republican officials.

The officials also said Hagel does not plan to run for the White House in 2008, despite earlier flirting with a candidacy.

The 60-year-old senator arranged a news conference for Monday in Omaha, Neb., to make his formal announcement. The officials spoke on condition of anonymity to avoid pre-empting the event.

The decision by Hagel is the latest in a string of setbacks for minority Republicans in the Senate, who must defend 22 of the 34 seats on the ballot next fall.