No wonder faith in the United States Senate is dwindling.

The chamber again failed to pass basic bipartisan legislation on Tuesday when it fell five votes short of the 66 needed to ratify a United Nations treaty that bans discrimination against people with disabilities.

This wasn’t just a slap in the face to the most vulnerable among us.

Thirty-eight Republican senators turned their back on their own party’s legacy of helping those who face mental and physical challenges. Before the vote, former U.S. Sen. Bob Dole, 89, appeared on the floor in a wheelchair to support passage of the U.N. Convention on the Rights of Persons With Disabilities.

The nonbinding language in the treaty was inspired by the Americans with Disabilities Act of 1990. Dole — himself disabled by a World War II injury to his right arm — led that landmark effort to passage. Former President George H.W. Bush signed it into law.

Opponents argue erroneously this latest international treaty threatens U.S. sovereignty. They say it’s an assault on parental rights, too.

Such claims grossly mischaracterize the intent of the U.N. measure, which proposes no changes to U.S. codes. It was largely symbolic. The eight Republican senators who sided with the Democrats on this issue knew this.

Refusing to recognize an American value that guarantees people’s right to live with dignity is shameful.