Not all of the major Senate races in the country are filled out yet, but early in the 2012 election cycle, we’ve got a pretty good idea what the GOP needs to do to win back the majority.

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Here’s how it works:

The goal is essentially four seats, though the GOP could also win three seats and the presidency to gain an effective majority (the vice president would be the tie-breaker). But the real goal right now is four Senate seats, which would give the GOP a 51-49 majority, including independent Sen. Bernie Sanders (Vt.) on the Democratic side.

Republicans are heavily favored to win the seat of retiring Sen. Kent Conrad (D-N.D.), with Rep. Rick Berg (R) already running and no major Democrat in the race. In essence, it’s shaken out almost exactly like it did when Sen. Byron Dorgan (D-N.D.) retired last cycle, and the GOP skated to victory. That’s one that should be in the bag.

Next are the two incumbents that Republicans are counting on to even the score – Nebraska and Missouri. If current numbers are to be believed, the environment for Democrats in both states is toxic. Sen. Ben Nelson (D-Neb.), in particular, is in rough shape in a very conservative state. Sen. Claire McCaskill (D-Mo.), meanwhile, is in a swing state where President Obama is particularly unpopular.

If Republicans win those three states, they’ve drawn the score even. The rest of the states will then determine control of the Senate. If they don’t, Republicans probably won’t take the majority.

Even setting aside these three races, Republicans have more targets left. Democrats basically have two solid targets – Sens. Dean Heller (R-Nev.) and Scott Brown (R-Mass.), with the possible additions of the open seats in Arizona, Texas and Indiana, if Sen Richard Lugar (R-Ind.) loses his primary. All three of those are clearly red states, and plenty of pieces need to fall in place before victory would appear possible.

Heller is looking more vulnerable than Brown, mostly by virtue of the fact that he has a top-tier opponent in Rep. Shelley Berkley (D). In Massachusetts, much like Arizona, Democrats are waiting for a major candidate to emerge against the popular Brown. The longer it drags on, the less likely that looks, and the bigger Brown’s nearly $10 million advantage grows.

As for the GOP’s targets, it’s take your pick. Republicans appear to have their best chances of defeating Sens. Jon Tester (D-Mont.), and Sherrod Brown (D-Ohio), along with an open seat in Virginia and Sen. Joe Manchin (D-W.Va.). Beyond that, they could be competitive against Sen. Bill Nelson (D-Fla.) and for open seats in nominal blue states New Mexico and Wisconsin — both states where it looks like they will have big-name recruits.

Republicans also hold out hope of recruiting candidates that can win in Michigan and Pennsylvania, but so far it has been a tough slog. Ideal candidates in both races would be wealthy busi­ness­peo­ple (think freshman Sen. Ron Johnson in Wisconsin), who could fund much of their own campaigns.

If Republicans can count on three victories — and they’re bullish on all three right now — they will have more chances to win that tiebreaking seat than will Democrats. And that’s largely because, of the seats that are up for reelection in 2012, more than two-thirds of them are held by Democrats.

A few of these races crystallized in the second quarter, though we’re still waiting for some of the candidates to announce their fundraising totals.

With that in mind — to the line!

On to the line: None

Off the line: None

10. Massachusetts (R): Sen. Scott Brown has banked nearly $10 million for his 2012 campaign — a sum that will make defeating him an uphill battle. Massachusetts is still an overwhelmingly blue state, and City Year founder Alan Khazei raised $920,000 in the second quarter. But he also came in third in the Democratic primary for the 2010 special election — a record that makes a lot of Democrats wary. State party officials are still openly pining for Consumer Financial Protection Bureau founder Elizabeth Warren, which can’t make Khazei (or any of the other primary contenders) happy. (Previous ranking: 9)

9. New Mexico (D): State Auditor Hector Balderas (D) turned in a surprisingly competitive fundraising quarter, raising $400,000, while Rep. Martin Heinrich (D-N.M) raised $485,000. Balderas is looking more and more like a contender everyday, which means this could be a seriously competitive primary. On the GOP side, Lt. Gov. John Sanchez’s fundraising report should give an indication of how competitive he is with former congresswoman Heather Wilson. (Previous ranking: 8)

8. Wisconsin (D): The field here is (slowly) starting to take shape. Rep. Tammy Baldwin (D) is moving closer to a run for the seat being vacated by Sen. Herb Kohl (D). Should former senator Russ Feingold (D) decide to get in, Baldwin wouldn’t have much of a chance in the primary. Without Feingold in the race, she’s a strong primary candidate and has a decent $1.1 million on hand — both boding well for a possible matchup with the more moderate Rep. Ron Kind (D-Wis.). Former governor Tommy Thompson is still the likely Republican nominee, but he could very well face a very tough primary. This race won’t likely take off until the current recall elections finish. (Previous ranking: 7)

7. Ohio (D): This is the big gainer for this week. State Treasurer Josh Mandel (R) beat all expectations for his first quarter as a candidate, raising $2.3 million and outraising Sen. Sherrod Brown (D) by more than $800,000. Mandel is just 33 years old, and having just won statewide office eight months ago, the jury was out on just how strong a challenger he was. Now, at least, we know he can perform one aspect of running for office exceedingly well. He will likely be the top non-incumbent fundraiser in any Senate race this quarter. (Previous ranking: 10)

6. Virginia (D): Not far behind Mandel was former Democratic National Committee Chairman Tim Kaine, who pulled in $2.25 million and doubled-up on former senator George Allen (R). Allen had a one-quarter head start on Kaine, and Kaine still has more money in the bank today. We still expect this race to be close, but Kaine looks stronger than he did last week. (Previous ranking: 5)

5. Montana (D): It was a good quarter for Sen. Jon Tester (D), who raised $1.2 million this quarter to bring him to $2.3 million cash on hand. Rep. Denny Rehberg (R) has yet to release his numbers for his first whole quarter in the race. The way Montana is trending, this will be a very close race no matter what, and it will take a lot of money for either candidate to win. Both sides like their chances here. (Previous ranking: 6)

4. Nevada (R): Rep. Shelley Berkley (D) outraised newly appointed Sen. Dean Heller (R) $1.2 million to $1.05 million, trumping him for the second straight quarter. Republicans say Berkley benefits from being Senate Majority Leader Harry Reid’s (D-Nev.) pet project, but a win is a win. Of concern for Berkley, though, should be primary opponent Byron Georgiou, who has turned aside efforts to clear the field for Berkley and has self-funded his way to $1.5 million cash on hand. He’ll be a real nuisance for Berkley. (Previous ranking: 4)

3. Missouri (D): Republicans remain bullish on beating Sen. Claire McCaskill (D), largely because Missouri is proving to be a very difficult state for every Democrat not named Gov. Jay Nixon (D). Obama’s numbers here have been bad, and McCaskill – known as a strong campaigner – will really have to turn it on if she is to get a second term. Her saving grace could be a so-so GOP field, which is led by Rep. Todd Akin (who raised just $512,000 in the second quarter) and former state Treasurer Sarah Steelman (who raised less than $200,000 in the first quarter). (Previous ranking: 3)

2. Nebraska (D): Republicans are losing the money race here, too. Attorney General Jon Bruning (R) had an especially disappointing fundraising quarter, with only $334,000 raised. And now that state Sen. Deb Fischer (R) is in the race, the GOP primary battle might be harder and uglier than expected. Sen. Ben Nelson (D), on the other hand, raised $910,000 this quarter to bring him to $2.9 million in the bank for what will surely be the fight of his political life. (Previous ranking: 2)

1. North Dakota (D): If Rep. Rick Berg (R) doesn’t win this seat, it’s either a really bad day for Republicans or a stirring comeback story for future-Sen. Earl Pomeroy (D). (Previous ranking: 1)

Rachel Weiner contributed to this report.