That’s partly because the presidential race is so close, and its battlefield is so narrow. Just four weeks before Election Day, fewer than 10 states are in play for the presidential contest, which allows for separate dynamics to take hold in House, Senate and gubernatorial races elsewhere.
There is also a paradox at work. While the amount of territory being contested in the presidential race is relatively small, “this is the largest Senate map that I can remember, certainly in a decade,” said Guy Cecil, executive director of the Democratic Senatorial Campaign Committee.
The same is true among House races, said Mike Podhorzer, political director of the AFL-CIO, though he said that could be because so many of them have been under the radar in this presidential election year.
“It looks like suddenly a lot more races are in play,” he said. “But I think a lot of them have been in play all along, just people didn’t know about it.”
Many of the most competitive House races are taking place in what Speaker John A. Boehner (R-Ohio) calls “orphan districts,” places that the presidential campaigns are all but ignoring, and where there is not even a hotly contested Senate race.
And even in some of the battleground states, candidates say they are all but ignoring what is happening at the top of the ticket.
Former House member Charlie Wilson, one of a handful of ex-lawmakers seeking to return to Congress, said he cannot count on President Obama’s performance in Ohio to carry him over the top in his conservative southeastern district.
“I run my race, and he runs his, and I can’t mix the two,” Wilson said.
Once-a-decade redistricting also has changed the equation. In some of the battleground states, such as Ohio and Virginia, it has strengthened the hold that Republican incumbents have on their districts and made them less vulnerable to the outcome at the top of the ticket.
But in California, where only one House seat changed parties over the past decade, the newly drawn lines have created something the state usually doesn’t see in congressional elections: suspense.
This year, the district lines have been so altered by a new nonpartisan reapportionment process that at least four of California’s 53 congressional races — all of them in seats currently held by Republicans — are rated as tossups by the authoritative Cook Political Report.
In recent weeks, the political tide has turned ever so slightly in House Democrats’ favor, particularly in late September as GOP presidential nominee Mitt Romney stumbled.
Still, to gain the 25 seats they need to return to the majority in the House, Democrats probably need to defeat at least 35 Republican incumbents. That appears unlikely, although Republicans concede privately that their ranks are likely to be reduced somewhat.