I would add one comment. In 2006 several dozen state legislators across the Midwest, including my home state of ND were not reelected.
Long time conservatives were unexpectly defeated. It appears that left-wing groups were raising money and quietly (and legally) sending it to Democratic candidates.
We learned this several months later-I believe I learned about it on Free Republic. We should have been aware in January, 1997 of the left’s ability to raise money.
We lost a good conservative congressman here in Michigan with Tim Walberg. The local paper said he wasn’t bad but he wasn’t bringing enough pork to the area so they endorsed the democrat.