This year, however, we have a seeming contradiction: The polls are pointing toward a wave in the House, with an average projected gain of 35 to 40 seats for Democrats and a popular vote win of 8 to 10 points.6 And yet, Democrats are at risk of losing several of their own Senate seats, which could offset any gains they may make among GOP-held seats and make it much harder for Democrats to take control of the Senate.

One way out of the dilemma for Democrats is if their incumbents in the Senate aren’t in quite as much trouble as the polls show — and our fundamentals calculation suggests that could be the case. Below is a comparison of polls and fundamentals in each seat held be an elected Democratic incumbent. Note that elected incumbent excludes appointed incumbents such as Tina Smith in the Minnesota special election; we’ll deal with her race in the next installment.

A handful of Democrats, such as West Virginia’s Joe Manchin, Ohio’s Sherrod Brown and Pennsylvania’s Bob Casey, are running slightly ahead of their fundamentals, but most Democrats are underperforming them. Florida, North Dakota and Missouri, where polls show near toss-ups in races that the fundamentals suggest should be Democratic-leaning, are the most important cases. Montana’s Jon Tester and Indiana’s Joe Donnelly, although they lead in most polls, also fall into this category, as fundamentals suggest they should have a slightly clearer advantage. Polls also show New Jersey’s Bob Menendez in a somewhat competitive race, when fundamentals imply Republicans should have no business competing in New Jersey in such a Democratic-leaning year — even accounting for Menendez’s corruption scandal.