Republican presidential candidate Sen. Rand Paul (R-KY) has an idea to keep the country safer: stop admitting any immigrant from the Middle East.

“We have to have a pause on immigration from the Middle East till we can get a handle on ‘are we admitting people who want to attack and kill us?'” Paul said on CNN Monday.

“We have 150,000 students here from the Middle East. Do we know where they all are? Do we know they are in school? Do we know that they haven’t overstayed their visas?” Paul said.

As Paul struggles to break through in a crowed Republican primary field, the senator’s proposal is going beyond simply barring Syrian refugees from coming to the U.S.

Paul introduced legislation last month that required the Department of Homeland Security to “suspend issuance of visas to nationals of countries with a high risk of terrorism” until new security checks could be met. Paul’s bill called on all current visa holders from some Middle Eastern countries to be screened and fingerprinted to assure they were not engaging in terrorist activity. Then, before DHS admitted more individuals, Paul’s bill called on DHS to complete an entry and exit system that ensured no immigrant overstayed their visa.

“Before we make the haystack bigger, before we admit millions of new people into this country, I think we have to push pause and have a moratorium on new immigration from the Middle East,” Paul said.