US Rep Chris Smith, a Republican from New Jersey, joined a news conference Tuesday in Lakewood, where Aharon Sofer grew up.
Smith says that U.S. And Israeli officials are "leaving no stone unturned" as they try to find the 23-year-old rabbinical student.
Sofer has been missing since Friday when he went hiking with a friend in the Jerusalem Forest.
Israeli police say they are pursuing all avenues in the investigation, including the possibility that Sofer may have fallen victim to an attack by Palestinian militants.