“You know, as a conservative, I’m a believer in following the plain text of the Constitution, and I think in this case the 14th Amendment is pretty clear, and that would involve a very, very lengthy constitutional process,” Ryan told Kentucky’s WVLK radio station on Tuesday.

Under the 14th Amendment, citizenship is granted to all people born in the U.S., even if their parents aren’t citizens, a concept known as “birthright citizenship.” The mainstream legal consensus is that a constitutional amendment would be required to change that.

Hours earlier on Wednesday, Trump reiterated his desire to end birthright citizenship, claiming “many scholars agree” the practice is not protected by the 14th Amendment.

“So-called Birthright Citizenship, which costs our Country billions of dollars and is very unfair to our citizens, will be ended one way or the other,” he tweeted. “This case will be settled by the United States Supreme Court!”

Although Ryan signaled his opposition to an executive order to end birthright citizenship, the speaker did not offer any possible repercussions for Trump if he proceeded with such an order.