Barr, who is 59 years old, was a Georgia Congressman from 19-95 to 2003 and left the Republican Party two years ago.
He helped lead Bill Clinton's impeachment. Some analysts say his candidacy could hurt republican John McCain's chances in the race.
The Field of Presidential Candidates Grows
5/12/2008 "I'll be seeking nomination of the Libertarian party of which I am a lifetime member."
Barr made the announcement Monday morning but must first win the libertarian nomination at the party's convention later this month.
