Former Sen. Gary Hart (search) will not return to politics, announcing Friday that he would not challenge Colorado Sen. Ben Nighthorse Campbell (search) for his Senate seat.

"After responsibly responding to supporters from the national and state Democratic parties and discussions with family members, I believe the best contribution I can make to the current national debate is to continue writing and speaking on our nation's economic, foreign policy and security issues, especially those exacerbated by the policies of the current Bush administration," Hart said in a statement.

Hart, 67, a former two-term senator and one-time presidential frontrunner, had considered the Senate bid for months.