By the time you are asked to do a breath test, the police have "probable cause". They get to that probable cause because you have answered questions ("yes, I was drinking"), and likely participated in a field sobriety test, both actions are essentially waiving your 5th amendment rights.
Yes, it is cons utional.
When you are pulled over, remember, it is a police investigation that you are not required to cooperate with, beyond giving them your license and registration.
"Have you had anything to drink?"
"I am not going to answer that question." (5th amendment)
"Can you walk this line?"
"No thank you." (5th amendment)
If they want to give you a ticket for speeding or no turn signal or such, sign that promise to appear, but beyond that I am pretty sure the 5th amendment covers most things they will ask of you.
I'm sure our resident lawyers can probably vouch for this. , please correct me if my understanding is incorrect.