More Democratic challengers have out-raised Republican incumbents and candidates than ever before — including in at least 73 House races for open seats, which are traditionally easier to flip.

More Democrats turned out in House primaries than Republicans this cycle — the first time that has happened since 2008.

Democrats have had a double-digit lead over Republicans in the generic congressional ballot in the last month.

Cook Political Report now rates 42 GOP-held seats as toss-up or worse. In 2010, there were 36 Democratic-held seats rated this way.

Republicans are pulling TV ads for vulnerable GOP incumbents in places like Kansas, Pennsylvania and Colorado.