The retiring lawmaker explained, "I support what the president wanted to do on border security, but I do not support the way he has been advised to do it. It is unnecessary and unwise to turn a border crisis into a constitutional crisis about separation of powers when the president already has congressional funding authority to build 234 miles of border wall that he requested in his January 6 letter to the Senate."
Alexander echoed other Republicans in warning, "There is no limit to the imagination of what the next left-wing president could do to harm our country with this precedent."
Speaking to reporters after his speech, Alexander said that if Trump took his advice, he could avoid a possible GOP rebellion, Politico reported.
The House has already passed a resolution to block Trump's declaration, while three Senate Republicans — Susan Collins (Maine), Thom Tillis (N.C.) and Lisa Murkowski (Alaska) — have said they will support the resolution when it comes before the upper chamber.
All Senate Democrats are expected to vote for the measure, meaning only one more Republican would need to break with their party to ensure its passage. Alexander stopped short of disclosing whether or not he would be the deciding vote, but did say "many Republican senators who can speak for themselves share" his views on the declaration.
Alexander added, "We've never had a case where the president has asked for money, been refused the money by Congress, then used the national emergency powers to spend it anyway. To me, that's a dangerous precedent."