BOTH parties and MOST politicians are corrupt.
I think it's funny how often I see this claim from people who support the biggest grifter in US politics today -- or probably, ever. To be clear, I'm talking about Donald Trump. If we actually enforced the constitutional clause against emoluments he'd have several hundred more indictments, and his kids would also be heading for prison.
The truth, I think, it is that most politicians are not corrupt, at least by proper definition of the word. I think all of them try to flex their opinions in the direction that will get them more campaign donations -- and many of them are very flexible -- but I think few of them take bribes (in the sense of cash that goes to them personally, not their campaigns). Nearly all congressmen use inside info obtained from their positions to trade stocks, and that's why we see so many of them who didn't come into politics with money getting wealthy. That's wrong, and we should make it illegal (my proposal is that all of them and their families should be required to publish their trades 24 hours before they make them), but it's not corruption. I'm also very suspicious of politicians who leave office and take extraordinarily high-paying jobs in industries they used to regulate. I don't think this is necessarily corruption, but it often is. I'm actually less skeptical of the speaking fees many of them command; I think those are largely legitimate, in the sense that the organizations who pay them actually think they're getting that much value from the speaking engagement, mostly in the form of prestige.
There are, of course, some politicians who really are corrupt, and unfortunately I think our system actually encourages this. We need stronger anti-corruption laws, laws that penalize even the appearance of corruption, and we need to pay out politicians better. In the absence of that, we need to prosecute all provable corruption to the fullest extent of the law. But I think most of them do stay on the right side of the law.