They just can’t help themselves. The fringe right of the Republican Party – paranoid or of some other diminished capacity – seems utterly unable to deal in reality, dwelling instead in a bizarre landscape produced by its own fever dreams.

In that unhappy place, a treaty that holds up an American law as a model for the rest of the world is a prospect to be feared. Even the support of conservative Republicans like Sen. John McCain and former Senate Majority Leader Bob Dole – undeniably brave and honorable men – isn’t powerful enough to break the spell.

That happened last week when the Senate voted 61-38 to ratify the Convention on the Rights of Persons with Disabilities. Though supporters vastly outnumbered opponents, the vote still fell short of the constitutionally required two-thirds majority, or 67 votes.

The treaty, patterned on the Americans with Disabilities Act, forbids discrimination against disabled people. As described by Sen. John F. Kerry, chairman of the Senate Foreign Relations Committee, the treaty would encourage other nations to develop protections such as this country’s.

The treaty would be overseen by the United Nations, which was enough to send the Chicken Little right into paroxysms of fear. Former Sen. Rick Santorum, a 2012 Republican presidential candidate, charged that the United States would be relinquishing its sovereignty to a U.N. committee and that said committee would, somehow, violate the rights of parents who home-school their disabled children. (Santorum also once worried that granting the right to consensual gay sex would lead to legalized incest, polygamy and more. He also thinks states should be allowed to ban birth control.)

It was all lunacy, but such is the mind-set of the zealots who have kidnapped the party of Lincoln. And in practicing their lunacy, they have told the rest of the world to be less like us, not more, and that it’s not important to worry about their citizens who have disabilities.

There may yet be hope. Kerry has pledged to bring the treaty back for another vote this winter. By then, Democrats will hold two additional Senate seats. That will pare the opposition. Then it will be up to the Senate, especially Republicans, to break the fever of enough Republicans to muster the 67 votes needed to approve this treaty.

It is, frankly, embarrassing for the United States, champion of the rights of the disabled, to reject this treaty based on the hallucinations of the far right. The treaty has already been signed by 155 nations and ratified by 126, including Great Britain, France, Germany and even China and Russia. There is no reason this nation should not join them.

There are many reasons for rational Republicans to wrest their party back from the zealots, but this is another. Who will trust the judgment of a party whose members reject their history as defenders of the downtrodden and, instead, act like members of a cult?