WASHINGTON – House Speaker Paul Ryan called Tuesday for a “pause” in Syrian refugees coming to the U.S. in the wake of the Paris attacks, and assembled a task force to bring legislation to a vote as soon as this week.

“Our nation has always been welcoming but we cannot let terrorists take advantage of our compassion,” Ryan, R-Wis., told reporters after a closed-door House Republican meeting. “This is a moment where it’s better to be safe than to be sorry, so we think the prudent, the responsible, thing is to take a pause in this particular aspect of this refugee program in order to verify that terrorists are not trying to infiltrate the refugee population.”

Republicans said the chairmen of national security-focused committees were working on legislation dealing with Syrian refugees that the House could vote on as early as Thursday, though it was not clear exactly what the legislation would involve. Thus far the numbers of Syrian refugees admitted to the U.S. from their war-torn homeland have been extremely limited and they are vetted in a lengthy process. Some Democrats denounced a rush to judgment on Capitol Hill and the presidential campaign trail.

Rep. Luis Gutierrez of Illinois likened the Republican reaction to the U.S. government turning away Jews fleeing Nazi Germany and placing Japanese in internment camps during World War II.

“Let us as legislators rise above petty politics, rise above sectarian fears … the underlying layer of xenophobia,” Gutierrez said on the House floor. “Let us maintain America’s commitment as a beacon of hope.”

The U.S. has admitted only about 2,500 Syrians since the civil war erupted in that country in the spring of 2011, but Obama administration officials want to admit 10,000 more this year. They announced that goal earlier this fall after a photograph of a little Syrian boy washed up on a beach sparked calls for compassion, including from some congressional Republicans.

Thus far the administration has not backed off the goal. Attorney General Loretta Lynch defended the vetting process in an appearance before the House Judiciary Committee Tuesday, saying: “We have the benefit of having that robust screening process which Europe doesn’t have.”

But pressure is mounting following Friday’s brutal attacks in Paris. The Islamic State group claimed responsibility and there were indications that one of the perpetrators might have entered France with a Syrian passport, potentially amid waves of refugees seeking haven in Europe.

Republican congressional aides said lawmakers are getting swamped by calls from constituents demanding action to ensure the U.S. is protected from such threats. The issue has emerged as a test for Ryan just weeks after he was sworn in as the new House speaker.

“Even amongst the most pro-immigration wings of the Republican Party there is a sense that national security absolutely has to come first,” Republican Rep. Mick Mulvaney of South Carolina said after leaving Tuesday’s Republican meeting. “So we’re trying hard not to overreact. But at the same time if there’s a threat to national security that has to take priority.”

Similar calls are coming from presidential candidates, and a number of GOP governors have announced plans to try to keep out Syrian refugees, though they appear to lack legal authority to do so. One Democratic governor – New Hampshire’s Maggie Hassan – also said the United States should halt the acceptance of Syrian refugees until intelligence and defense officials can ensure a strong vetting process.

Hassan is challenging Republican Sen. Kelly Ayotte in next year’s Senate race.

Even some Republicans who previously supported accepting more refugees are joining the call to clamp down. Sen. Lindsey Graham of South Carolina, a Republican candidate for president, was one of those. On Monday he called for a “timeout” in such admissions.

In a telephone call with journalists Tuesday, senior officials from the State Department, Homeland Security Department and U.S. intelligence community emphasized that screening for Syrian refugees is the most rigorous for any set of travelers wishing to enter the United States.

The checks – conducted by multiple intelligence and law enforcement agencies – include an interview overseas, biometrics, fingerprinting and biographical investigations to determine if individuals are truly worthy of refugee status or if they pose security risks. Syrians are subject to additional, classified controls, said the officials, who briefed reporters on condition they not be identified by name.

The current acceptance rate for Syrians is around 50 percent. The other half includes denials and cases pending further investigation.

Of the roughly 2,500 Syrians the U.S. has taken in since the civil war erupted, about half are children. Another 2.5 percent are people over 60. Only about 2 percent are single men of combat age. The overall pool is almost evenly split between males and females.