Though House Speaker Paul Ryan has endorsed Donald Trump, he has made it clear he does not support some of his policies and said he's prepared to take him to court should the presumed Republican presidential nominee move forward with one of them.

"I would sue any president that exceeds his or her powers," the Wisconsin Republican told the Huffington Post in an interview published Friday when asked about Trump's proposed Muslim ban.

Trump has vowed to ban Muslims from entering the United States and even said he would attempt to do so without congressional approval.

However, Ryan said he is unsure if Trump enacting the Muslim ban would actually overreach his presidential authority.

"That's a legal question that there's a good debate about," Ryan said, citing the 1952 Immigration and Nationality Act.

Ryan also clarified his endorsement of Trump, saying it did not give him "a blank check" and that he is still working toward "real unity" between the likely GOP nominee and the rest of the party.

However, Trump hasn't yet crossed the line in terms of what Ryan will accept from him.

"I don't know what that line is, but right now, I want to make sure that we win the White House," Ryan said, adding that he and Trump "still got work to do" to find harmony.

Ryan was hesitant to endorse Trump, deciding not to do so in May until the two of them met. This month, Ryan endorsed Trump, and this week said it is " not my plan" to rescind that endorsement.