President-unelect Rick Santorum made his triumphant return to the Capitol on Monday afternoon and took up a brave new cause: He is opposing disabled people.

Specifically, Santorum, joined by Sen. Mike Lee (R-Utah), declared his wish that the Senate reject the U.N. Convention on the Rights of Persons With Disabilities — a human rights treaty negotiated during George W. Bush’s administration and ratified by 126 nations, including China, Russia, Iran, Cuba, Syria and Saudi Arabia. 

The former presidential candidate pronounced his “grave concerns” about the treaty, which forbids discrimination against people with AIDS, who are blind, who use wheelchairs and the like. “This is a direct assault on us,” he declared at a news conference.

Lee, a tea party favorite, said he, too, has “grave concerns” about the document’s threat to American sovereignty. “I will do everything I can to block its ratification, and I have secured the signatures of 36 Republican senators, all of whom have joined with me saying that we will oppose any ratification of any treaty during this lame-duck session.”

Lame or not, Santorum and Lee recognized that it looks bad to be disadvantaging the disabled in their quest for fair treatment. The former senator from Pennsylvania praised Lee for having “the courage to stand up on an issue that doesn’t look to be particularly popular to be opposed.”

Courageous? Or just contentious? The treaty requires virtually nothing of the United States. It essentially directs the other signatories to update their laws so that they more closely match the Americans with Disabilities Act. Even Lee thought it necessary to preface his opposition with the qualifier that “our concerns with this convention have nothing to do with any lack of concern for the rights of persons with disabilities.”

Their concerns, rather, came from the dark world of U.N. conspiracy theories. The opponents argue that the treaty, like most everything the United Nations does, undermines American sovereignty — in this case via a plot to keep Americans from home-schooling their children and making other decisions about their well-being.

The treaty does no such thing; if it had such sinister aims, it surely wouldn’t have the support of disabilities and veterans groups, the U.S. Chamber of Commerce, Republican senators such as John McCain (Ariz.) and John Barrasso (Wyo.), and conservative legal minds such as Boyden Gray and Dick Thornburgh.

But the opposition is significant, because it shows the ravages of the Senate’s own disability: If members can’t even agree to move forward on an innocuous treaty to protect the disabled, how are they to agree on something as charged as the “fiscal cliff”? And although the number of senators who actually oppose the treaty — such as Lee, Pat Toomey (Pa.) and Jim DeMint (S.C.) — is probably quite small, Lee’s boast of 36 signatures means he has persuaded enough of his colleagues to block action, at least temporarily. (Treaties require a two-thirds vote in the Senate to pass.)

Santorum made an emotional appeal, even bringing his daughter Bella, who has a severe birth defect, to the Senate hearing room for the event. “There’s no benefit to the United States from passing it,” he said, as Bella wriggled in her mother’s arms. “But what it does is open up a Pandora’s box for the most vulnerable among us: children with disabilities.”

Yet the opponents couldn’t agree on how this box would be opened. “Do I believe that states will pass laws or have to pass laws in conformity with the U.N. edict?” Santorum asked himself. “Do we have to amend IDEA?” the Individuals with Disabilities Education Act. “I don’t have any fear anytime soon that IDEA will be amended. But I do have concerns that people will go to courts and they will use this standard in this convention.”

This was contradicted by the next man at the microphone, home-schooling advocate Mike Farris, who pointed out that the document has a provision stating that “you can’t go to court automatically. You must have implementing legislation first” — the very thing Santorum says he does not expect to happen.

Still, their spurious theory of a U.N. takeover of parenting was enough to lead Lee and Santorum to oppose a treaty that would extend American values worldwide and guarantee disabled people equal treatment, and freedom from torture and exploitation.

Santorum justified his opposition by saying that other countries wouldn’t actually enforce the provisions. “It does not provide any moral leadership,” he said.

But in this fight against rights for the disabled, Santorum doesn’t have a leg to stand on.

danamilbank@washpost.com