Here is an election-night guide that will help you gauge whether the Democratic wave is just a ripple or a tsunami.

The fundamental election dynamic has not changed much since the beginning of the year. Democrats hold big advantages in all of the national indicators. The president’s job approval rating is low, just under 40 percent. Americans prefer a generic Democratic candidate to a Republican one by close to 15 percent, and nearly two-thirds believe the country is going in the wrong direction. These consistently negative indicators point to significant losses for Republicans in the House, Senate and governorships. The question has always been: How many?

Looking at the individual race polling, Democrats are likely to pick up four to six seats in the Senate (with a 50-50 Senate the most likely outcome), 20 to 25 seats in the House, and five to eight governorships. But there is still some volatility, especially in the House, with some question about how the respective bases of the parties will turn out.

In the Senate, it is simple. Watch Missouri, New Jersey, Tennessee and Virginia. If Democrats win three, they should control the Senate.

In the House, watch nine vulnerable Republican candidates, three each in the states of Connecticut, Kentucky and Pennsylvania.

In Connecticut, watch Christopher Shays, Rob Simmons and Nancy Johnson, in order of vulnerability. If Democrats pick up zero seats, then their national gain is likely to be lower than expected, maybe still enough to eke out a majority in the House, but perhaps not. If they win one seat, expect a 20-seat gain; two seats, a 25-seat gain. And if all three incumbents lose, Democrats are likely to gain 30-plus.

Use the same system in the Philadelphia suburbs, where Curt Weldon is now the most vulnerable, Jim Gerlach second, and Michael Fitzpatrick the hardest to knock off. 

Then, go to Kentucky and watch Geoff Davis, who is an even bet to win, then Anne Northup, who has a small edge in her race, and Ron Lewis, whose district should not be competitive, but who has shown up on many watch lists as the news has gotten worse for Republicans.

In these three states, which are in the eastern time zone and whose polls will be closed by 8 p.m., you can measure the height of the wave on a scale of 0 to 9.

Finally, if you are looking to gauge the lingering effects of the Mark Foley scandal, watch the seats of Tom Reynolds, Deborah Pryce, the open Minnesota-6 seat and Mark Foley’s former seat.

When the Foley scandal hit, it had a dispiriting effect on Republicans, who thought they might have been gaining ground. While the general effect on mood and momentum is hard to measure, the scandal had an immediate and dramatic effect on several seats, and there are some indications that these effects may be receding somewhat.

Tom Reynolds and Deborah Pryce saw post-Foley polls put them down 10 to 15 points, but recent polls show tight races. In Minnesota-6, the Foley scandal initially helped Democratic challenger Patty Wetterling, but recent polls show Republican Michelle Bachmann strengthening.  And some Republicans even believe that they can win Mark Foley’s seat, although I have my doubts. If these four races go to Republicans, then the Foley scandal was a small distraction. Lose them all, and Republicans will further curse the name of Mark Foley.

So if you are planning to go to bed on election night before the all the returns come in, this guide may set the tone for your sweet dreams or nightmares, whatever the case may be.

Fortier is a research fellow at the American Enterprise Institute.