I think that it is too easy to be overly optimistic about the November elections at this stage

From Charlie Cook writing for the National Journal:

Privately, some Democratic pollsters say that they are routinely seeing districts where Democratic incumbents are running only even with relatively unknown GOP challengers. In other districts where the Republican challengers are reasonably well known, the incumbents are often running 5-10 points behind, a rather extraordinary development at this point.

In the Senate, while the odds still favor Democrats holding on to a narrow majority, it is not only mathematically possible for the GOP to capture a majority this year, but it has become plausible. The odds of Democrats capturing even one currently Republican-held seat appear to be getting longer. Meanwhile, Republicans are running ahead or roughly even in 11 Democratic-held seats, one more than necessary for control of the Senate to flip. It's still a tall order but not crazy to say that Republicans will win the Senate. . . .