The US Supreme court broke politics when it opened the floodgates to money. Now candidates don't have to care if the party is against them since they have ready sources of cash from every lunatic group out there. The Supreme Court is also responsible for ignoring blatant gerrymandering of congressional districts, which ensures candidates don't really have to worry about elections any more.
And unlike our parties there is no veto by the party leader over prospective candidates down there. Which is why you get moronic candidates like that cowboy in Alabama.
They need to get the money out of politics. When you need $15 million to run a campaign you have to sell yourself to the big money interests or just not bother to run. They need to stop the gerrymandering so congressmen are more wary about what their district might feel about an issue. And the Republicans in particular, need to stop loonies from running under their party banner.