In our final rankings of the 2014 Senate field, Republicans are well-positioned to win the six seats they need to retake the majority and have a reasonable chance to claim eight or even nine seats if the national environment continues to move against Democrats in the final days.

Of the 13 races in which both parties are spending heavily, Republicans have the top eight pickup opportunities. That includes races that are effectively already over -- open seats in Montana, South Dakota and West Virginia -- as well as badly endangered incumbents like Sens. Mark Pryor (Ark.), Mark Begich (Alaska) and Mary Landrieu (La.). Perhaps most surprising are Republicans' prospects in Colorado and Iowa -- two seats that were long assumed to be likely Democratic holds but, as of today, look like they are tilting slightly toward Republicans.

Republicans have only three seats in any danger -- Kansas, Georgia and Kentucky. Sen. Mitch McConnell (Ky.) appears to have moved ahead of the persistent challenge from Democrat Alison Lundergan Grimes, and likewise, Georgia's runoff system is making it more difficult for Democrat Michelle Nunn to pull of an upset there. Sen. Pat Roberts (Kan.) remains in serious danger and, if one Republican incumbent loses, it will probably be Roberts.

Taken in totality, Republicans have a number of paths to the six seats they need to take control heading into the 114th Congress. As Democratic Senatorial Campaign Committee executive director Guy Cecil rightly pointed out in an interview with Plum Line's Greg Sargent this week, there are "10 races that are within three points." Given that competitiveness, it's possible that Democrats see most close races tip their way and save their Senate majority. Possible. But not probable.

Below are the rankings of the 13 most competitive races in the country. The No. 1 race is the most likely to switch parties, and the rest are ranking in order of that likelihood.

To the line!

13. Kentucky (Republican-controlled): Last week, Democrats spent a lot of time insisting that Alison Lundergan Grimes was in striking distance of Senate Minority Leader Mitch McConnell (R-Ky.). This week? Not so much. The new Bluegrass Poll, which showed the race very close last week, came out Thursday night and gave McConnell a 48 percent-to-43 percent edge. Democrats say it's closer than that. But they don't say they're ahead, either. (Previous ranking: 13)

12. New Hampshire (Democratic-controlled): A WMUR/UNH poll released Thursday showed Sen. Jeanne Shaheen (D) leading Republican former senator Scott Brown by eight points. Democrats think Brown made a big mistake when, they argue, he got tripped up by New Hampshire geography in the final televised debate on Thursday, but the moderator later said Brown was actually right. Brown still has a chance, but Shaheen is popular and has the edge heading into the weekend. (Previous ranking: 12)

11. Georgia (R): For a moment there, it was looking like Democrat Michelle Nunn might flirt with getting 50 percent of the vote on Election Day – a number that would win her the race outright and avoid a January runoff. Then, a few polls showed Republican David Perdue up. The last two polls have been tied. The point here is that Nunn would be hard-pressed to win a January runoff. She really wants to not only beat Perdue on Election Day, but also get to 50 percent, which is tougher with the libertarian candidate taking a few percentage points. (Previous ranking: 10)

10. North Carolina (D): Democrats feel good about their ground game here and they like the campaign that Sen. Kay Hagan (D) has run. She appears to have slight edge in the polls over Republican Thom Tillis. Democrats need to hold this seat more than Republicans need to pick it up. The national pressure on Hagan to hang on to her narrow advantage is immense. (Previous ranking: 11)

9. Kansas (R): Ever since the National Republican Senatorial Committee all-but-took-over the campaign of Sen. Pat Roberts (R), he's done what he needed to put himself back in contention -- bringing in big-name GOP surrogates, keeping up a full campaign schedule and attacking independent Greg Orman hard. But what has it done? Polls show it has basically pulled him back to even with Orman. This is toss-up heading into the final stretch. (Previous ranking: 8)

8. Iowa (D): Let’s give state Sen. Joni Ernst (R) a slight advantage for now. She leads narrowly in most polls, and the early vote has been surprisingly good for Republicans. This is still a swing state, and there’s plenty of time left in the early-voting period. Rep. Bruce Braley (D), though, finds himself a somewhat unlikely underdog. (Previous ranking: 9)

7. Alaska (D): How’s this for intrigue: Republican Dan Sullivan led every poll (albeit narrowly) for two months. But the final poll here, from local pollster Ivan Moore, has Sen. Mark Begich (D) up by six points. We’re not sure many folks believe the poll -- which also shows longtime Rep. Don Young (R-Alaska) in serious danger -- but polling in Alaska is notoriously tough, so nobody is counting this one as over just yet. And that uncertainty, plus developments in Colorado (see below), lead us to drop this behind the Centennial State. (Previous ranking: 6)

6. Colorado (D): Democrats just shake their heads when asked what happened to Sen. Mark Udall (D). The most common explanation for the incumbent's current plight is that he got caught napping when Rep. Cory Gardner (R) reversed course and decided to run. No matter the reason, Udall will enter Election Day as the underdog. But Democrats believe there is the potential for very high turnout thanks to the state's new vote-by-mail system -- a scenario, that if it comes to pass, could save Udall. (Previous ranking: 7)

5. Louisiana (D): A recent poll showed a tight race on Tuesday between Sen. Mary Landrieu (D) and Rep. Bill Cassidy (R), but when it comes to the likely runoff, Cassidy led 48 percent to 41 percent. As we’ve noted, runoff polling isn’t terribly reliable this far out. But as long as Cassidy can rally supporters of tea party favorite and likely third-place finisher Rob Maness (R), he would be a clear favorite in the runoff. (Previous ranking: 5)

4. Arkansas (D): A poll from the University of Arkansas on Thursday showed Rep. Tom Cotton (R) leading Sen. Mark Pryor (D) by 13 points -- Cotton's biggest lead to date. But the poll, for what it’s worth, was among “very likely” voters, not just the usual "likely" voters. Still, it’s hard not to count that as a pretty good sign for Cotton. (Previous ranking: 4)

3. South Dakota (D): The Democratic push to put this state in play has fallen flat. As Rick Weiland (D) is fighting with his national party, Republican former governor Mike Rounds has regained his firm lead and independent former GOP senator Larry Pressler has fizzled. After a brief scare, the GOP is once again poised to pick up this seat. (Previous ranking: 3)

2. West Virginia (D): Rep. Shelley Moore Capito (R) got into this race almost two years ago. (She announced  around Thanksgiving 2012). Her persistence and candidate quality ensures victory. (Previous ranking: 2)

1. Montana (D): Rep. Steve Daines (R) is going to walk into the Senate after the Democratic field imploded. (Previous ranking: 1)