Gov. Mitch Daniels of Indiana said early Sunday he would not become a candidate for the Republican presidential nomination, telling supporters in an e-mail that concerns from his family were the overriding factor in deciding to stay out of the race.
Later Sunday, Tim Pawlenty, a former governor of Minnesota, announced his candidacy for the GOP nomination. An aide to his campaign said last week that the announcement would come today in Iowa.
Daniels' decision not to run deflated the hopes of many in the Republican establishment. The popular second-term governor was a budget director in the White House under President George W. Bush.
"In the end, I was able to resolve every competing consideration but one," Daniels said. "The interests and wishes of my family is the most important consideration of all. If I have disappointed you, I will always be sorry."
He is the latest in a string of prominent Republicans to decline a presidential bid, leaving the field without a clear front-runner less than eight months before the first voting could begin.
Mike Huckabee, the former Arkansas governor; Gov. Haley Barbour of Mississippi; and Donald Trump, the businessman and reality TV star, have all announced in recent weeks that they would not seek the Republican nomination. Sarah Palin, a former governor of Alaska, has yet to declare her intentions. But the rest of the field is coming together.
Former Massachusetts Gov. Mitt Romney, who sought the party's nomination in 2008, also plans to run. Former Utah Gov. Jon Huntsman is also a potential candidate.
Candidates already in the race include former House Speaker Newt Gingrich, Rep. Ron Paul of Texas, businessman Herman Cain and former New Mexico Gov. Gary Johnson.
Information from the New York Times, Washington Post and Associated Press was used in this report.