I meant specifically the party leadership (since US political parties don't have formal representation) - If you look at McConnell and even Trump (when not hyperbolizing) you'll see they very consistently message that everyone should be vaccinated. One of the things I sort of appreciate about Trump is the fact that, even while getting booed at most of his events over it, he's continued to mention that he was vaccinated and it's perfectly safe. (This isn't meant to devolve into things we think about Trump - I just wanted to call out that single point).
Politicians need to be smart enough to know when to present a united front - they have a much greater visibility into the damage this pandemic is causing to the country by being completely immersed in dealing with it as their vocation. Yes, some people might still disagree (I've got no illusions or hope for a fully united consensus) but those people should be fewer, harder to see and much more ostracized than what the US political arena looks like today.
Politicians are also quite capable from detaching their personal beliefs from their public beliefs - Dick Cheney notably held to the party line opposing gay marriage while having an openly gay daughter. There are a litany of other examples of failing to practice what you preach - so yea, even if they privately hold these beliefs it's quite reasonable to assume that Mitch McConnell and others would be able to coerce them into falling in line when talking to the public.
