Effect of the Presidential race/debate on downticket races?

[Leaper]

One concern I’ve seen from liberal/Democratic commenters on blogs is that Republicans have been energized by Mitt Romney’s debate performance, going from “critical to cheerleaders” overnight, and that would cause them to vote more enthusiastically for, and donate more money to, Republican Congressional candidates as well as Romney.

On one hand, I see the point, and it feels valid. On the other hand, it never really felt like loyal Republicans were willing to sit out the election unless Romney suddenly turned out to be the reincarnation of Hitler or Keynes (heck, maybe not even then).

What do you all think? For that matter, the basic question may be: how much of an effect, historically, has a Presidential candidate had on candidates of his party running in other races that year?

[Randvek]

@Leaper

On one hand, I see the point, and it feels valid. On the other hand, it never really felt like loyal Republicans were willing to sit out the election unless Romney suddenly turned out to be the reincarnation of Hitler or Keynes (heck, maybe not even then).

I am willing to believe that Democrats rely quite a bit on turnout (and thus enthusiasm) to make ground in Congressional races.

I have a much harder time believing the same about Republicans. It seems like they have fewer people leaning their way, but those that do are more likely to vote regularly.