Missouri Sen. John Ashcroft, once considered a potential Republican rival to George W. Bush, endorsed the Texas governor today, saying "it's good to be on a winning team."

Ashcroft is the 31st senator to sign to sign on to the Bush campaign, with number 32 expected to be Sen. Connie Mack (Fla.) later this afternoon.

Ashcroft's backing is significant first because Bush is eager to demonstrate support in the Senate, where his closest rival, Sen. John McCain (Ariz.), has long served.

In addition Ashcroft is a well-known social conservative with an active base of supporters.

Ashcroft is so well thought of in social conservative circles that Christian Coalition founder Pat Robertson repeatedly hinted last year that Ashcroft was among his favorites in the large field of potential GOP candidates. Robertson stopped short of endorsing Ashcroft, who eventually announced that he would see re-election to the Senate instead of the presidency.

"Obviously, he [Ashcroft] has a national following and has worked on a number of issues that are close to the governor's heart," said Bush campaign spokesman Mindy Tucker. Among those issues, Tucker said, was charitable choice -- the welfare reform provision that allowed religious organizations to contract with the federal government to offer welfare services.

In a speech this morning at a community center here with hundreds of Bush supporters cheering him on, Ashcroft said the Texas governor was "going to be a great president because he won't just govern America, he will lead America."

Bush has drawn large crowds here in South Carolina over the past few days as he has stumped for votes in what will be the first southern state to hold a primary next month. More than 1,000 people turned out at each of two events the campaign held Tuesday.

Today, Bush continued to try to engage McCain on taxes, arguing that his rival's plan did little to help people on the lowest economic rung.

But Bush was forced to defend himself at a news conference here this morning against news reports that a campaign aide coached a supporter to make negative statements about McCain in a campaign advertisement.

At the news conference, Bush denied knowledge of the ad. His spokeswoman, Karen Hughes, standing in the back of the room, interrupted to say there was an advertisement that talked about McCain, but the woman in question had not been coached. Nonethess, she said, the ad would not run.

"I'm going to treat my friend and opponent with respect," Bush said. "He deserves to be treated with respect. He is a buddy. But he is not right on the tax plan, and I hope people analyze the full extent of his tax plan."