Do Republicans have any chance of winning back the Senate in November?

The answer to that question, strange as it sounds, may lie in the battle for control of the House. Not since 1930 has control of the House flipped without the Senate flipping also. On the other hand, control of the Senate has changed hands a couple of times since World War II without the House flipping — think, most recently, of 1980 (or, with an asterisk, of 2000).

[IMGCAP(1)]In October 2006, it already looked pretty likely that Democrats were going to grab control of the House. But the Senate still appeared to be up in the air. Yet one by one, all the pieces fell into place. It really seemed like a game of dominoes. We knew on election night that Democrats had won the House; we didn’t know for sure about the Senate until two days later, when then-Sen. George Allen (R) conceded in Virginia.

By sheer numbers alone, in competitive election years, the minority party should always have a better chance to make gains in the House because there are simply more potential targets of opportunity — and more conceivable paths back to the majority. This year is no exception. The Republicans need 40 seats to win back the majority in the House, and the experts say that anywhere from 50 to 80 seats will be very competitive. So if, say, the Republicans fall short in their efforts to knock off freshman Rep. Betsy Markey (D) in Colorado’s 4th district, maybe they can surprise Rep. John Salazar (D) in Colorado’s 3rd. There are any number of ways to get to 40.

This would seem like good news for the GOP, and in most ways it is. But it can also be daunting to party strategists with limited financial resources. The electoral playing field becomes like a roulette wheel. Where do you place your chips? Sure, there are some pretty safe bets for the Republicans this year, and both parties know it: Louisiana’s 3rd district. Tennessee’s 6th. Idaho’s 1st. And so on, at least for a dozen seats or so.

But after that? You pays your money, you takes your chances.

The Republicans deserve credit for recruiting so many good candidates and putting so many seats in play. But it’s hard to tell now — and it may even be hard to tell in October — which districts could be the difference for the GOP between seizing the majority and falling a little short.

The Senate, though, where Republicans need to pick up 10 seats, is a different story. Without a doubt, there is a path to victory for the GOP. But it’s awfully narrow.

We know we can automatically take 15 safe races off the table (though Scott Brown’s success in the Massachusetts special election has some Republicans in unlikely places thinking big — keep dreaming, fellas). And we know we can automatically move North Dakota and probably Delaware into the GOP column. So then the target becomes eight.

The next likeliest to fall? Arkansas and Nevada. Or, if you prefer, Nevada and Arkansas. Then victory actually becomes visible. Which Democratic seats are then in the most jeopardy? Indiana. Illinois. Pennsylvania. Colorado. So close to the majority, if they all fall, that Republicans can taste it.

But where does the GOP go from there? Pundits have suggested Sens. Barbara Boxer (Calif.), Russ Feingold (Wis.), Patty Murray (Wash.) or appointed Sen. Kirsten Gillibrand (N.Y.) as the next obvious targets. Call us skeptical of these as opportunities, for now. And remember, Democrats have legitimate targets of their own, in Ohio, Missouri, New Hampshire and, to a lesser extent, Kentucky — and even longer-shot pick-up possibilities in North Carolina, Florida and Louisiana. How does that scramble the math?

One thing that Republicans have going for them is recent history: Since the late 1990s, almost all of the competitive Senate seats have moved in one direction. That trend was most dramatic in the last two election cycles: In 2008, Democrats won four of the five Senate races that Roll Call rated as “Tossups” a month before election.

In 2006, Democrats won all six Senate elections that we rated as “Tossups” a month before the election — and won Virginia, which we rated as “Leans Republican” a month out. Two years earlier, things went better for Republicans: they won six of the seven seats that we deemed “Tossups” a month before Election Day; in 2002, they won four of the six races we classified that way, plus the Georgia Senate race, which we had rated as “Leans Democratic” that October. And in 2000, which was more of a Democratic year (even as George W. Bush was — barely — winning the presidency), six of seven “Tossup” races went the Democrats’ way.

So we appear to have two historical trends at work this election cycle — and they’re more complementary than contradictory. But there are also an awful lot of political cross-currents at work here — more, it seemed, than there were in 2006 and 2008, when the political storyline was obvious.

Voters are still angry — if anything, they’re angrier than they were in the previous two cycles. Things look bad for Democrats — they will lose seats, plain and simple. But today, seven and a half months before Election Day, the Democrats have at least a small chance of shifting the political dynamic sufficiently to avoid a major bloodbath. That didn’t seem to be the case for Republicans at this point in the ’06 and ’08 cycles.