Actor is casting his vote for bipartisan '08 ticket

Sam Waterston is putting his star power to work in backing a movement aimed at promoting the political center rather than the left or right.

The star of "Law & Order" told George Stephanopoulos on ABC's "This Week" he has joined Unity '08, a group that would like to elect a bipartisan ticket to the White House.

"There's a huge majority of the American people who are ready for this, who are not represented in the current system. And this is an opportunity for those people to speak up," the actor said.

"I think by its existence it will have a beneficial effect on anybody who's running for president, because they will be obliged to look over their other shoulder at the center, and not simply address the partisan factions that have so much sway in primaries," Waterston said.