Mitt Romney scored a major endorsement Monday in his quest to solidify his conservative credentials, racking up the backing of Moral Majority co-founder Paul Weyrich.

Weyrich helped the late televangelist Jerry Falwell establish the group that nearly 30 years ago first sought to mobilize religious conservatives into the political process. He is a founder of the Heritage Foundation and currently is chairman and CEO of The Free Congress Research and Education Foundation.

"Governor Romney has outlined a blueprint to build a stronger America rooted in our common conservative principles. With a clear conservative vision to move America forward, he will strengthen our economy, our military and our families. More importantly, he already has an exceptional record of putting conservative values to work," Weyrich said in a written statement.

"His support and endorsement I think communicates that I am able to build upon the coalition that Ronald Reagan put together of social, economic and foreign policy conservatives," the Republican presidential candidate said of Weyrich at a campaign stop in Fort Lauderdale, Fla. "He is someone whose social conservatism is without question and his support of my campaign means a great deal to me."

Romney is locked in a race with former Tennessee Sen. Fred Thompson as each seeks to establish himself as the true conservative candidate and distinguish himself from Republican frontrunner Rudy Giuliani, who espouses more moderate views on issues like abortion and gun control.

Earlier Monday, Thompson announced that Shannon Royce, former executive director of the conservative Arlington Group, would be joining the campaign as grassroots and special projects director.

But Weyrich is also a heavy hitter among social conservatives, and could lend credibility to Romney among that group of voters. The endorsement comes on top of backing from Bob Jones III, of South Carolina's Bob Jones University.

Romney has also won the top spot in an Oct. 20 straw poll of "values voters" conducted by the conservative Family Research Council in Washington. Romney came in first with 1,595 votes, followed closely by former Arkansas Gov. Mike Huckabee, who got 1,565 votes.

That poll placed Giuliani in eighth place, second to last.

FOX News' Carl Cameron and Shushannah Walshe contributed to this report.