The script has most definitely been flipped on Senate battlegrounds in 2016.
This cycle, Republicans take nine of the 10 spots on Roll Call's list of the most vulnerable senators. That's a marked turn from 2014 , when there were nine Democrats and one Republican.
The list features just the incumbents, so the ultra-competitive open-seat races in Nevada and Florida are not included. And it should also be noted that senators in spots six through 10 are not nearly as vulnerable as those at the top of the list.
We'll update this list six months from Election Day, and again in the weeks leading up to Nov. 8, 2016.
1. Sen. Mark S. Kirk, R-Ill., 1st term Nobody on the ballot next year has a tougher re-election fight ahead than Kirk. Elected during the Republican wave in 2010, he is on the ballot this time in a mostly blue state during a presidential year.
Democrats have gone all in to defeat Kirk. Both the Democratic Senatorial Campaign Committee and EMILY's List have hammered the first-term lawmaker, and both have pledged their support to Rep. Tammy Duckworth, the leading Democrat vying to replace him.
(Rothenberg & Gonzales Political Report/Roll Call Rating: Tilts Democratic )
2. Sen. Ron Johnson, R-Wis., 1st term Pouring nearly $9 million of his own money into his first political campaign, Johnson won by fewer than 5 points in the GOP wave of 2010. In a state that votes Democratic at the presidential level, and with his Democratic predecessor, former Sen. Russ Feingold, vying for his old seat, Johnson’s path to re-election doesn’t look easy.
3. Sen. Patrick J. Toomey, R-Pa., 1st term For years, Republicans have said they can carry Pennsylvania's 20 Electoral College votes.
But not since 1988 has a Republican presidential candidate won the Keystone State. And that's bad news for Toomey, who just barely won this seat in 2010 — despite the GOP wave.
Sure, Democrats have a competitive primary here. Yet no matter whom Toomey faces, he's likely to have to overcome a strong Democratic presidential turnout to win.
(Rating: Tilts Republican )
4. Sen. Kelly Ayotte, R-N.H., 1st term Ayotte's path to re-election got a lot tougher when Democratic Gov. Maggie Hassan announced her Senate bid in October.
As the vice chairwoman of the Democratic Governors Association, Hassan has a national fundraising base to raise the kind of money necessary to compete.
And the Granite State has gone Democratic in five of the past six presidential contests — meaning Ayotte could be forced to convince a large number of voters to split their tickets.
(Rating: Tilts Republican )
5. Sen. Rob Portman, R-Ohio, 1st term Portman starts the election behind in polling against his likely Democratic opponent: former Gov. Ted Strickland.
But this race will probably to go down to the wire, as the Buckeye State is expected to be close at the presidential level.
And an $11 million war chest can go a long way for Portman to build support for his candidacy, as well as knock Strickland down.
(Rating: Leans Republican )
6. Sen. John McCain, R-Ariz., 5th term McCain is entering his third decade in the Senate, but with a presidential race at the top of the ticket, Arizona will likely be targeted by national Democrats this year who would offer organizational support to drive voters to the polls.
McCain has a strong challenger in Democratic Rep. Ann Kirkpatrick, who represents the only tossup district, which Mitt Romney won with 50 percent of the vote. The DSCC and EMILY's List have both pledged to support her effort.
(Rating: Republican Favored )
7. Sen Richard M. Burr, R-N.C., 2nd term When big-name Democrats, including former Sen. Kay Hagan , passed on this race, Burr looked like he might get a free pass, despite his dismal approval ratings . Democratic former state Rep. Deborah Ross doesn’t have wide name recognition across the state, and it remains to be seen how much money she can raise, but the latest Public Policy Polling poll shows her trailing Burr by only 4 points.
In this undeniably purple state, Burr’s fate is likely tied to the presidential race and whom Republicans select as their nominee. Obama narrowly carried the state in 2008, the same year Hagan won, before narrowly losing it four years later. (Rating: Leans Republican )
8. Sen. Roy Blunt, R-Mo., 1st term Blunt, who has been in Washington for more than two decades, is deeply rooted in this town — armed with his leadership role in the Senate, deep political ties in his home state and impressive fundraising strength. He appears tough to beat, but Missouri Democrats believe if anyone can do it, Secretary of State Jason Kander can.
Perhaps no one besides Kander has a more compelling case against Blunt. He served in Afghanistan while Blunt was in Congress; he fought for an ethics overhaul in Missouri while Blunt's family picked up new lobbying contracts; and, unlike Blunt, Kander is one of the country's youngest elected officials.
In presidential election years, Missouri voters have been known to split their tickets. In 2012, Sen. Claire McCaskill, D-Mo., received more votes in the Show-Me State than Republican presidential candidate Mitt Romney, buoyed, in part, by the outrage over Republican Senate candidate Todd Akin's "legitimate rape" comments. But even before that, Democrats won five of the six statewide offices up for grabs in 2008, the same year in which Obama lost to McCain there by less than 4,000 votes.
(Rating: Republican Favored )
9. Sen. Rand Paul, R-Ky., 1st term Though Kentucky has become a very red state during presidential election years, Paul — who has focused much of his attention on his long-shot presidential bid rather than his re-election effort – could find himself trying to make up ground next year.
Paul has transferred large sums of cash from his Senate account to both his presidential effort and to pay for Kentucky's Republican caucus, which he fought his own party leaders back home to get in order to run for president and the Senate at the same time.
On the Democratic side, state Auditor Adam Edelen, who was seen as a potential challenger to Paul, lost his bid for re-election, which sent Democrats scrambling to come up with their next move.
(Rating: Safe Republican )
10. Sen. Michael Bennet, D-Colo., 2nd term Bennet squeaked by in 2010, defeating now-Rep. Ken Buck by fewer than 2 points to win his first term.
In a state Obama carried twice, presidential turnout may boost the former DSCC chairman, who has had months without a challenger to build a massive war chest . And yes, Republicans have suffered a series of recruiting struggles here. But the 2014 Senate election, when then-Rep. Cory Gardner didn’t enter the race until March and went on to unseat Sen. Mark Udall, haunts Democrats and is encouraging Republicans. GOP businessman Robert Blaha isn't the party's first pick, but he does have the ability to self-fund. (Rating: Leans Democratic )
Related: Roll Call Race Ratings Map: Ratings for Every House and Senate Race in 2016 Get breaking news alerts and more from Roll Call in your inbox or on your iPhone.