Will the Republican party take action before it is too late?

Listening to the latest from President Trump I am growing more and more concerned that he is mentally unfit.
He has always played fast and loose with the facts and behaved petulantly and impulsively but it is getting worse.
I wonder if the stress of being president has pushed him too far and increased a preexisting mental illness.
I am not in favor of a President Pence but a president with dementia is worse.
The Republican party needs to bite the bullet and do right by America, and if they don't care about that I put it to them that the current situation is bad for the party and getting worse.
At the very least they need to immediately force a medical exam.