Senate Democrats did more than just expand their majority for the 113th Congress on Tuesday; they also inoculated themselves against a very tough map in 2014.

Now, we know. At the beginning of the 2012 election cycle, we (and everyone else) talked incessantly about how good the map was for Republicans and how the majority was in reach for them. And it was. Yet somehow Democrats walked away with a one- or two-seat gain (depending upon Angus King).

Sen. Al Franken (D-Minn.). (Eric Miller -- Reuters)

Well compared to the 2014 map, 2012 was tame.

As we've written in detail before, Democrats have to defend six incumbents in red states and six incumbents in swing states, while their best pickup opportunity is in Kentucky, a state that just went 60 percent for Mitt Romney in the presidential race.

Below, we rate the 10 seats that are most likely to flip in 2014. The top nine are all currently held by Democrats, and the 10th is Kentucky.

Now, none of this is to say that Democrats are doomed. If 2012 showed us anything, it's that Democrats can win in red states (Montana, North Dakota, Missouri, Indiana) and that candidates -- and campaign committees -- matter.

Lots of things have to shake out. But purely looking at the political lean of the states, the strength of the incumbents and the field of potential challengers, 2014 is a doozy for Democrats.

That said, now that they have somewhere between an eight-seat majority and a 10-seat majority AND the presidency (the vice president breaks ties), they now have much more room for error.

While Republicans could have won the Senate back this year by gaining just three seats and the presidency, they'll probably need to win six Senate seats to win the chamber in 2014. And that's a tall order -- even on this map.


Below is our inaugural Friday Line of 2014 Senate races, on which No. 1 is the most likely to flip and No. 10 is the least likely.

This list will change significantly in the coming months; for now, it's a baseline.

To the line!

10. Kentucky (Republican-controlled): The only GOP-held seat on this list will be tough for Democrats to pursue; after all, it's Kentucky. But Senate Minority Leader Mitch McConnell (R-Ky.) isn't quite bulletproof back home. A recent poll showed he has a 51 percent approval rating and a 42 percent disapproval. What's more, Democrats have some big names that could run against him. Gov. Steve Beshear (D) just won a resounding reelection victory in 2011 and can't run again in 2015. Other Democrats being mentioned include actress Ashley Judd (who has suddenly become more politically active) and Secretary of State Alison Lundergan Grimes.

9. Colorado (Democratic-controlled): Sen. Mark Udall's (D-Colo.) middle-of-the-road approval rating in a swing state makes this first-term senator one to watch in 2014. Rep. Cory Gardner (R) and former lieutenant governor Jane Norton (who ran for the Republican Senate nomination and lost in 2010) are two names to watch in Colorado if Republicans feel like they can knock off the incumbent. Gardner, in particular, is seen as the next big thing for the state GOP. Does he go after Udall or wait for Sen. Michael Bennet (D) in 2016?

8. New Hampshire (D): Democrats in New Hampshire had a big year in 2012, knocking off the state's two GOP congressmen and holding the governor's seat. In 2014, Sen. Jeanne Shaheen (D) will be up for a second term. Amazingly, the buzz seems to be that former senator John Sununu (R) might attempt a comeback, which would set up a third consecutive race between the two of them. Sununu won the first, while Shaheen won the second. Shaheen has pretty solid numbers, though, and incumbency matters.

7. Minnesota (D): Sen. Al Franken (D) won this seat by 312 votes in one of the best Democratic years in modern memory in 2008. He will have to defend it in President Obama's second term mid-term (a.k.a. “six-year itch”) election with national Republicans and conservatives gunning for him like no one else on the Democratic side. Former governor Tim Pawlenty, who would have likely been Republicans' best candidate, seems off the table now that he is a lobbyist. Rep. Michele Bachmann will be mentioned, but that prospect should send shivers down the spines of GOP strategists; her statewide numbers are terrible. We could see a rematch of Franken vs. former senator Norm Coleman (R), and also keep an eye on Rep. Erik Paulsen (R), who comes from the the best place to live in the entire country (and hometown of this Deputy Fix): Eden Prairie, Minn.

6. Arkansas (D): Sen. Mark Pryor (D-Ark.) basically got a pass in 2008, but Arkansas continues to drift toward Republicans (they now control all four of its House seats), and now-Sen. John Boozman (R) beat Sen. Blanche Lincoln (D-Ark.) like a rented mule in 2010 (21 points!). Don't expect Pryor to skate by again. The top name being mentioned to run against him appears to be Rep. Tim Griffin (R), a well-regarded former congressional aide who first won his seat in 2010.

5. Montana (D): When an incumbent runs radio ads out of cycle, it's a sure sign that a trouble could be brewing. Sen. Max Baucus (D-Mont.) did just that earlier this year, signalling that he is prepared for what could be a tough reelection race. The Senate Finance Committee chairman has served in the Senate since 1978, but he saw his popularity plummet when he headed up the effort to pass Obama's health-care bill. Popular outgoing Gov. Brian Schweitzer (D) has been mentioned as a potential primary challenger, but Schweitzer appears to have his sights set higher than the Senate. As for the general election, Republicans will have to do some soul-searching (and recruiting) after Rep. Denny Rehberg's (R) loss to Sen. Jon Tester (D) on Tuesday. Rehberg has now lost two Senate campaigns, to both Tester and Baucus, so Republicans will probably look elsewhere.

4. Louisiana (D): The Bayou State has turned heavily Republican in the past few election cycles, and even before that transformation was complete, Sen. Mary Landrieu (D) was a major Republican target every six years. Landrieu has never broken 52 percent in any of her three races for the Senate despite the fact that Republicans have fielded B-team candidates (at best) against her. Rep. Bill Cassidy (R) seems to be putting the pieces (and money) in place to challenge Landrieu, setting up a marquee race.

3. North Carolina (D): Sen. Kay Hagan (D-N.C.) could face a tough time in 2014 running in a state that gave its 15 electoral votes to Mitt Romney, elected a Republican governor, and netted the GOP at least three seats in the House. What's more, Hagan's approval rating is nothing to write home about. Democratic automated pollster Public Policy Polling found earlier this month that just 35 percent approved of the job she was doing, while 37 percent disapproved. Hagan, who unseated Republican Elizabeth Dole in 2008, should be among the senators most at risk in 2014.

2. Alaska (D): Sen. Mark Begich (D) beat longtime Sen. Ted Stevens (R) in 2008 when the late senator was caught up in some ethics issues, and now Begich has to hold a state that has long been a GOP stronghold and just went for Mitt Romney by double digits (55-42). Possible GOP opponents include Gov. Sean Parnell, Lt. Gov. Mead Treadwell, and 2010 nominee Joe Miller, who beat Sen. Lisa Murkowski (R) in a 2010 primary, but lost when Murkowski ran in the general election as a write-in candidate. Begich and Parnell recently got into a personal squabble over drilling in the Arctic reserve. Miller was hugely unpopular at the end of the 2010 general election.

1. South Dakota (D): Whether or not Sen. Tim Johnson (D) retires, this seat looks to be a prime pickup opportunity for Republicans. Popular former GOP governor Mike Rounds has already formed an exploratory committee for the Senate and would be formidable either against Johnson or for an open seat. If Rounds passes, which seems unlikely, Republicans would likely turn to Rep. Kristi Noem, who has held the state’s only congressional seat since 2010. If Johnson steps aside, look for Democrats to turn to former congresswoman Stephanie Herseth Sandlin, whom Noem unseated in 2010 but remains well-regarded.

Chris Cillizza and Sean Sullivan contributed to this report.