Relatives of four Americans missing or detained in Iran told Congress on Tuesday of milestones missed — weddings, graduations, birth of grandchildren — and asked U.S. officials to push for their release in negotiations with Tehran on a nuclear deal.

Lawmakers from both parties said that if Tehran doesn't release them immediately, they would not trust the Iranian government to adhere to terms of the deal international negotiators are rushing to finalize before the end of the month.

"If top Iranian officials cannot be counted on to assist these wrongfully jailed Americans, can they be counted on to honor the commitments they make at the negotiating table?" asked Republican Rep. Ed Royce, chairman of the House Foreign Affairs Committee. "Call me a skeptic."