Sen. Kay Hagan (D-N.C.), up for reelection during this midterm election cycle, works with her staff off the Senate floor last month. (Melina Mara/The Washington Post)

The scene is set. With primary season nearing an end, we know who the nominees will be in almost all of the races that will decide control of the Senate this November.

The GOP establishment largely got the candidates it wanted and avoided any incumbents losing primaries. And Republicans are playing offense in upwards of 10 Democratic-held seats, needing to take six of them to steal control of the Senate.


That appears increasingly likely. Democrats, though, continue to poll very competitively in two states the GOP probably shouldn't have to defend: Kentucky and Georgia. Losing either would be a huge spoiler when it comes to the GOP's winning calculus.

At this point, that winning calculus appears to include three likely takeovers: South Dakota, West Virginia and Montana, the last of which featured appointed Sen. John Walsh (D-Mont.) recently dropping out over revelations of academic plagiarism.

Beyond that, the GOP has three red states and three swing states they are pursuing. Winning just half of them would likely deliver the Senate.

Here's our latest list of the top 11 races. As always, No. 1 is most likely to flip control.

To the line!

11. Georgia (Republican-controlled): Businessman David Perdue's (R) primary runoff win over Rep. Jack Kingston means he faces off against Democrat Michelle Nunn. Most recent polling shows Perdue with a slight edge, but the National Republican Senatorial Committee just launched a multimillion-dollar ad campaign here. Clearly, they see Nunn as a real threat, despite Georgia's continued GOP lean (it's turning purple more slowly than most people think). (Previous ranking: 10)

10. Colorado (Democratic-controlled): Sen. Mark Udall (D-Colo.), after some uncertainty, announced last month that he would oppose ballot measures, pushed by Rep. Jared Polis (D-Colo.), that were aimed at cracking down on fracking. Eventually, the measures were scrapped anyways, but the decision was somewhat surprising from a senator who has often aligned with environmentalists. Democrats fretted rather openly about the measures hurting Udall on the ballot in November. Rep. Cory Gardner (R), though, remains an underdog. (Previous ranking: 9)

9. Kentucky (R): The Democrats' best shot at a pickup might be in the Bluegrass State, where polling continues to show one of the tightest races in the country. Despite this, though, election models of 2014 have Senate Minority Leader Mitch McConnell (R-Ky.) as a strong favorite over Democrat Alison Lundergan Grimes – in large part because the state is so red. FiveThirtyEight says McConnell has an 80 percent shot to win, and the Post pegs his chances even better than that. We'll see if those models are accurate. (Previous ranking: 7)

8. Alaska (D): The big news Friday was that Joe Miller, the 2010 GOP nominee with strong tea party ties, said that he would support the GOP nominee and not run a third-party campaign if he lost the primary Aug. 26 Tuesday. Anything other than a win by former state attorney general Dan Sullivan in that primary would be a pretty big surprise, and Miller's assurance has got to make Republicans breathe a little easier. But Sen. Mark Begich (D) is doing a lot of things right. (Previous ranking: 8)

7. Iowa (D): A recent Roll Call story by Alexis Levinson captured the state of this open seat race nicely: State Sen. Joni Ernst (R) moved through the Iowa State Fair doing a lot of hugging — both people she knew and people she didn't. Democratic Rep. Bruce Braley, meanwhile, delivered a dry policy address from the fair's legendary soapbox. Ernst is clearly the candidate with the momentum in this race but, as Levinson noted, Braley might be more closely aligned to the preferred policies of the electorate. (Previous ranking: N/A)

6. North Carolina (D): Senate Democrats' campaign arm just dropped a stunning $9.1 million into a new advertising campaign here, reinforcing that this is the race to watch this fall. It's the least conservative of the four Romney states where Democrats are running for reelection. If Sen. Kay Hagan (D) can hold on to her seat, Democrats give themselves some critical breathing room in the battle for the majority. If state House Speaker Thom Tillis wins (R), the GOP path to the majority becomes much wider. (Previous ranking: 5)

5. Arkansas (D): Rep. Tom Cotton (R) has led the last six public polls of this race — all by between two and four points. Shortly before that, an NBC News/Marist poll incredibly showed Sen. Mark Pryor (D) ahead by 11. We tend to think this is a pretty pure toss-up right now. (Previous ranking: 6)

4. Louisiana (D): It seems likely no one will clear 50 percent threshold in the all-party primary and that Sen. Mary Landrieu (D) will face a runoff against Rep. Bill Cassidy (R-La.) on Dec. 6. Just imagine the November frenzy in the Bayou State if the Senate majority ends up riding on the outcome. (Previous ranking: 4)

3. West Virginia (D): It seems more and more like Montana and South Dakota are lost causes for Democrats. But West Virginia's not there yet. The Democratic super PAC Senate Majority PAC recently bought broadcast advertising time there, and Secretary of State Natalie Tennant (D) has run a surprisingly strong campaign. That doesn't mean she's going to upset Rep. Shelley Moore Capito (R). It just means West Virginia's not a done deal. (Previous ranking: 2)

2. Montana (D): The decision by Walsh not to seek a full term this fall in the wake of revelations about plagiarism takes an already-difficult race and makes it virtually impossible for Democrats. Democrats will decide on their nominee at a special state convention this weekend. Freshman state Rep. Amanda Curtis seems like the likeliest pick and cuts a very interesting profile. But this race is probably a lost one for Democrats, and Rep. Steve Daines (R) is the heavy favorite to be the next senator. (Previous ranking: 3)

1. South Dakota (D): The good news for Democrat Rick Weiland: Former GOP senator Larry Pressler is pulling nearly one-fifth of the vote as an independent. The bad news: Pressler has raised just $50,000 for the campaign, self-funding another $50,000. As we’ve written before, third-party candidates with little chance of winning tend to see their vote totals fall off at the end. Former governor Mike Rounds (R) is still the big favorite unless something changes in a major way. (Previous ranking: 1)

3:38 p.m. Correction: This post previously said the RNC issued a Rule 11 letter in the Louisiana Senate race to enable it to support Rep. Bill Cassidy (R). The RNC says it issued no such letter. The post has been updated accordingly.