In what is among the sorriest moments for the 112th Congress, Senate Republicans on Tuesday blocked ratification of a United Nations treaty that banned discrimination against people with disabilities.

No sound reason for opposition existed, as the treaty is modeled after the Americans With Disabilities Act, which Republican President George H.W. Bush signed into law in 1990. Senators were merely being asked to affirm what's already the law of the land in the United States.

The U.N. treaty was signed by President Obama in 2009. It's also supported by 155 nations and 126 countries. But the Senate has yet to ratify the treaty, and this week fell five votes short of the two-thirds majority needed.

Ratification would have required that people with disabilities who travel outside our country be treated with dignity and offered the same freedoms, rights and reasonable accommodations mandated on American soil. Veterans groups and others lobbied for the measure.

While 38 Republicans cast "no" votes, eight joined with Democrats in supporting the treaty, including Arizona Sen. John McCain, a former prisoner of war who lobbied for the bill alongside Democratic Sen. John Kerry of Massachusetts. Opponents ridiculously insisted the treaty would lead to U.N. interference with American sovereignty.

Among the saddest moments in this shameful chapter was when former Senate Majority Leader and 1996 presidential candidate Bob Dole, a Kansas Republican, was on hand to watch the debacle. The 89-year-old veteran, who lost the use of his right arm and hand during World War II, sat off to the side, slumped in a wheelchair.

Like many of us, he must have wondered how so many in his party could turn their backs on the disabled.