A prominent and powerful evangelical Christian leader, James Dobson, said yesterday that the Mormon faith practiced by Governor Romney of Massachusetts could pose a serious obstacle if Mr. Romney makes a bid for the Republican presidential nomination in 2008.

“I don’t believe that conservative Christians in large numbers will vote for a Mormon but that remains to be seen, I guess,” Mr. Dobson said on a syndicated radio program hosted by a conservative commentator, Laura Ingraham.

Mr. Dobson, the founder of the Colorado-based Focus on the Family, did not say why Christians would fail to support Mr. Romney. Mr. Dobson also acknowledged that the governor’s stands on social issues are similar to those of many religious conservatives.

“He’s a nice guy. He’s a very attractive man. He’s got a beautiful wife and a lot of his principles and values are consistent with ours,” Mr. Dobson said. A spokesman for Mr. Romney, Eric Fehrnstrom, had no immediate comment.

While some Christians have denounced Mormonism as a heretical sect, not all conservative Christians agree that Mr. Romney’s faith will hurt him with the religious right.

“If he’s pro-life, pro-family, I don’t think he’ll have any problem getting the support of evangelical Christians,” a founder of the Moral Majority, Rev. Jerry Falwell, told the Clarion-Ledger of Jackson, Mo. earlier this year.