Sen. Rand Paul (R-Ky.) said on Sunday that his border security plan is the “only way” to win conservative support for comprehensive immigration reform.

Paul said his “Trust but Verify” amendment offers a key element that other proposals do not: it would allow Congress to vote every year on whether the country’s borders are secure.

“You’re only going to get the conservatives, particularly a Republican House, to pass immigration reform if we as conservatives are reassured that the border is controlled and that we get to vote on whether the border is controlled,” said Paul on Fox News Sunday.