Gravel, who had been running for the nomination as a Democrat, will pursue the Libertarian nod during the party's convention in Denver May 22-25, The New York Times reported Thursday.

"Whether or not some of our delegates will accept Mike Gravel with some of his positions, that has yet to be seen," said Andrew Davis, a spokesman for the Libertarian National Committee.

Gravel's support of universal healthcare funded by a national retail sales tax could turn off some Libertarian members, Davis said. Also, 15 candidates already are seeking the nomination.

In announcing his decision to supporters via e-mail, Gravel said the Democratic party "is no longer the party of FDR" and supports sustaining war, the military-industrial complex and imperialism.

"By and large, I have been repeatedly marginalized in both national debates and in media exposure by the Democratic leadership," he wrote.

Gravel has lived in Virginia for several years.