WASHINGTON, Jan. 24 - A coalition of major conservative Christian groups is threatening to withhold support for President Bush's plans to remake Social Security unless Mr. Bush vigorously champions a constitutional amendment banning same-sex marriage.
The move came as Senate Republicans vowed on Monday to reintroduce the proposed amendment, which failed in the Senate last year by a substantial margin. Party leaders, who left it off their list of priorities for the legislative year, said they had no immediate plans to bring it to the floor because they still lacked the votes for passage.
But the coalition that wrote the letter, known as the Arlington Group, is increasingly impatient.
In a confidential letter to Karl Rove, Mr. Bush's top political adviser, the group said it was disappointed with the White House's decision to put Social Security and other economic issues ahead of its paramount interest: opposition to same-sex marriage.
The letter, dated Jan. 18, pointed out that many social conservatives who voted for Mr. Bush because of his stance on social issues lack equivalent enthusiasm for changing the retirement system or other tax issues. And to pass to pass any sweeping changes, members of the group argue, Mr. Bush will need the support of every element of his coalition.
"We couldn't help but notice the contrast between how the president is approaching the difficult issue of Social Security privatization where the public is deeply divided and the marriage issue where public opinion is overwhelmingly on his side," the letter said. "Is he prepared to spend significant political capital on privatization but reluctant to devote the same energy to preserving traditional marriage? If so it would create outrage with countless voters who stood with him just a few weeks ago, including an unprecedented number of African-Americans, Latinos and Catholics who broke with tradition and supported the president solely because of this issue."
The letter continued, "When the administration adopts a defeatist attitude on an issue that is at the top of our agenda, it becomes impossible for us to unite our movement on an issue such as Social Security privatization where there are already deep misgivings."
Some Senate Republican leaders were not optimistic on Monday about the amendment's prospects this year.
"I think if we had the vote right now we'd come up short," said Senator Rick Santorum, the Pennsylvania Republican who is a member of the leadership and one of the amendment's most vocal backers in Congress. "We'd like to bring it up when we have the best possible chance of getting it passed."
The members of the coalition that wrote the letter are some of Mr. Bush's most influential conservative Christian supporters, and include Dr. James C. Dobson of Focus on the Family, the Family Research Council, the Southern Baptist Convention, the American Family Association, Jerry Falwell and Paul Weyrich.
Several members of the group said that not long ago, many of their supporters were working or middle class, members of families that felt more allegiance to the Democratic Party because of programs like Social Security before gravitating to the Republican Party as it took up more cultural conservative issues over the last 20 years.
Tony Perkins, president of the Family Research Council, declined to talk about the letter, but said, "The enthusiasm to get behind his proposals is going to require that he get behind the issues that really motivated social conservative voters."
So, in other words, a quid pro quo: these folks are saying "You give us a ban on gay marriage, and we'll give you a raid on the Social Security system. Even though some old folks will wind up eating dog food who otherwise wouldn't, banning gay marriage is more important to us than seeing that the elderly live in dignity."
I cannot but be disgusted by this.