By Christi Parsons and Paul Richter, Tribune Washington Bureau

WASHINGTON — The Obama administration has told Iran that its nominee for ambassador to the United Nations is “not viable,” but the White House did not outline steps it might take to derail the potential appointment.

Jay Carney, the White House spokesman, said President Barack Obama has serious concerns about Tehran’s choice of Hamid Aboutalebi, who has acknowledged that he was a member of the student group that led the 1979 armed takeover of the U.S. Embassy in Tehran.

Carney did not say if what he described as “diplomatic jargon” meant the State Department would refuse to grant a visa to Aboutalebi. His visa application to enter the United States as a diplomat has been stalled for months.

The White House adopted the harsher tone a day after the Senate unanimously passed a measure barring Aboutalebi from entering the United States. The bill was a rare legislative victory for its lead sponsor, Sen. Ted. Cruz (R-TX).

As host nation of the U.N. headquarters in New York, the United States normally admits appointed representatives and diplomats of U.N. member states, although with some exceptions.

There was no immediate impact on the negotiations that resumed Tuesday in Vienna between Iran and six world powers over Tehran’s disputed nuclear development program.

AFP Photo/Fabrice Coffrini