“The Syrian situation is the most pressing humanitarian crisis of our time,” Mr. Durbin said in an interview, “and if we do not respond in a positive and proactive way, we’re going to have future generations asking, ‘Where were you?’”

The administration has scrambled to pick up the pace of resettling Syrian refugees, officials say. The Departments of State and Homeland Security sent a surge of personnel to Jordan this year to interview about 12,000 refugee applicants referred by the Office of the United Nations High Commissioner for Refugees, and officials have begun processing cases in Beirut, Lebanon, and Erbil, Iraq. But the numbers remain stubbornly low.

Germany has not said how many refugees it might accept. In 2015, it registered 447,336 new applicants for asylum, about 25 percent of them Syrians.

A program begun by the United States in 2014 to allow Central American children with a relative in the country to qualify as refugees has approved only 300, an administration official said. Secretary of State John Kerry announced in January that he would create another initiative to admit as many as 9,000 refugees from El Salvador, Guatemala and Honduras after processing outside the United States, but the program has not begun.