Edit: Writing this out I think, I'm probably part of the problem. Voters should remember who they voted for and benchmark the results against their campaign pledge. Keeping politicians responsible with the little power we individuals have.
But, fortunately they are just losing supporters as people opt out of fealty to any party. Independents are the largest voting bloc now, although they have partisan leanings, they are underrepresented.
Inevitable consequence of a representive democracy. Parties are chosen based on electability, which is merely a proxy for good policy. This means parties that don't optimise for electability at the cost of good policy will eventually be outcompeted by those that do.
(It's for this reason Graeber sometimes jokingly (?) called representative democracy "elective aristocracy".)