Rep. Jim Clyburn (search), an influential South Carolina lawmaker who has endorsed Dick Gephardt (search), is touting the Democratic presidential candidate in a new television commercial to air in the first-in-the-South primary state this week.

The ad marks the first time in the election cycle that a presidential candidate is using a high-profile supporter to reach voters.

Clyburn, a six-term Democratic congressman and leading member of the Congressional Black Caucus (search), endorsed Gephardt on Wednesday. All nine of the Democratic candidates had courted Clyburn, whose endorsement could sway voters in the Feb. 3 primary. Minorities could make up almost half of the likely primary voters.

In the 30-second ad that will run statewide, Clyburn says Gephardt "will be a president South Carolina can count on" and that he has witnessed Gephardt's "concern and commitment up close."

"As Democratic leader, he fought for Clinton's economic plan that helped create 22 million jobs. Together, we stood up for middle-class families against NAFTA (search) and the China Trade Deal," Clyburn says.

Endorsement ads typically are broadcast in the final weeks of a campaign and the practice will become more common as candidates gain the backing of favored political sons and daughters in a state.

Gephardt has shifted some of his money and attention to South Carolina over the past few weeks, believing that a win in Iowa, which holds its caucuses Jan. 19, and a win in South Carolina could position him as the alternative Democrat to front-runner Howard Dean.

Gephardt first went up on the air in South Carolina last week, using a biographical commercial that had run in Iowa and New Hampshire. Before that, he had been using radio ads for more than a month in the state. However, he has spent most of his ad dollars -- more than $1 million -- in Iowa, and has not been on the air in New Hampshire, which has its primary Jan. 27, since September