The US Senate passed legislation on Monday seeking to bar Iran's proposed UN Ambassador, Hamid Abutalebi, from entering the United States.
The legislation, introduced by Texas Republican Senator Ted Cruz, would prevent "known terrorists" from entering the United States to serve as UN Ambassadors.
The Senate passed the measure by voice vote.
The possibility that Abutalebi may have played a role in the 1979-1981 hostage crisis has outraged some of the US embassy workers held by the Iranians for 444 days.
Several lawmakers had said they were infuriated that Iranian President Hassan Rouhani would make such a choice, and the State Department had expressed concern.
The United States, which severed diplomatic ties with Iran in 1980 during the hostage crisis, is generally required to allow UN diplomats to come to New York under its host country agreement with the United Nations. However, it can under limited circumstances refuse to grant visas to such diplomats.
New York Democrat Charles Schumer, the third-ranking member of his party in the Senate, said he was pleased about the vote and that he and Cruz, normally on opposite sides of policy decisions, had discussed the legislation.
"We ought to close the door on him, and others like him, before he even comes to the United States, and that's exactly what this bill will do," Schumer said in a statement.
The measure must be approved by the House of Representatives before it could be sent to President Barack Obama to consider signing it into law. There was no immediate word from House leaders about its prospects in that chamber.