Obviously, past results are not a guarantee of future performance: Democrats are not going into the 2014 House midterms in an overexposed position, because they took such a beating in 2010, losing 63 seats and regaining only eight seats this year. It’s hard to see how Democrats could lose the 48 seats that the “in” party lost in 1958, 1966, and 1974. Also, with the way the current lines are drawn to form so many one-party districts, it would take a heckuva wave election to move a lot of seats in either direction. The House appears to have reached a kind of a partisan equilibrium; the GOP has a good chance of holding onto control for the rest of the decade, barring self-destruction resulting in a tidal wave.
But in the Senate, with only one Republican-held seat up (Susan Collins in Maine) in a state not carried by Mitt Romney by at least 8 points, the GOP seems to have little exposure. At the same time, Democrats have four seats in states that Romney carried by 15 or more points (Mary Landrieu in Louisiana, Mark Pryor in Arkansas, Jay Rockefeller in West Virginia, and Tim Johnson in South Dakota), with two more in states that Romney won by 14 points (Max Baucus in Montana and Mark Begich in Alaska) and two others in swing states (Kay Hagan in North Carolina and Mark Warner in Virginia).
Significantly, though, as Republicans painfully learned in 2012, overexposure doesn’t necessarily mean that Democrats will lose seats. This year, Democrats had 23 seats up to only 10 for Republicans, yet Democrats managed to score a net gain of two seats, defying all odds. In 2014, Democrats are once again overexposed, with 20 seats up compared with just 13 for the GOP. At least on paper, 2014 should be an opportunity year for Senate Republicans, assuming they don’t nominate horrifically flawed, weak, or self-immolating candidates, as they did, over the strenuous objections of party leaders and strategists, in 2010 and 2012