Democrats are starting to feel confident they will win two key Senate races — and are within striking distance in several other states that would give them a majority when the next president takes office.

The minority party believes it can pick off Illinois and Wisconsin from Senate Republicans, but that still leaves five core battleground states balanced on a knife’s edge as the GOP tries to protect its 54-seat majority.


The landscape is littered with traps for both parties as Democrats go on the attack against Republican incumbents around the country.

The preferred Democratic candidates are thriving in Florida and New Hampshire, but both face challenges inside and outside their parties. Democrats are stuck dealing with primaries in Ohio and Pennsylvania while also struggling to match GOP incumbents’ strong fundraising. And in Nevada, Republicans have a rare opportunity to pick off a Democratic seat, but they have to fight through a Latina Democrat and an increasingly Latino electorate that has grown hostile to them in presidential years.

That presidential environment is of paramount importance: It will be very difficult for Republicans to hold the Senate if they lose another presidential race, while Democrats would have an almost impossible time winning the Senate back if they lose the White House.

Further down the map, the only other Republican opportunity to gain a seat is in Colorado, where national Republicans — finally — think they've found a candidate and could make a strong run in a divided state. Democrats also hope to go after a few red states, and some of their early efforts in Missouri, Arkansas and Arizona, look to be bearing fruit, even as their hopes in Kentucky and Louisiana have withered.

Donald Trump and national security’s sudden reemergence as a top issue reminded us in 2015 how quickly things can change. For now, though, here are the 2016 Senate races, ranked in order of each seat’s likelihood to change partisan control in November:

1. Illinois — GOP Sen. Mark Kirk running for reelection (Previous ranking: 1)

Kirk didn't drop out of the contest; he hasn't committed a gaffe in months; his signature issue of national security is on the rise; and his team argues that Illinois won't be as strongly blue without President Barack Obama on the ticket.

But he's still a marked underdog. Democratic Rep. Tammy Duckworth has national security credentials of her own, and she outraised Kirk by $400,000 in the third quarter, closing his cash-on-hand advantage. Republicans are still hoping businesswoman Andrea Zopp can dislodge Duckworth in the Democratic primary, and recent news in Illinois could help Zopp’s criminal justice reform-focused campaign. But time for Zopp to catch fire is running out, and it's not clear Kirk would fare much better against her, anyway.

2. Wisconsin — GOP Sen. Ron Johnson running for reelection (2)

Johnson, like Kirk, may remain an underdog to former Democratic Sen. Russ Feingold no matter how many things break his way. Johnson has used his bully pulpit as chair of the Senate Homeland Security Committee to add national security heft to his previous economy-focused résumé, just as security has jumped back to the top of the issue heap for voters. Two state-specific outside groups ready to attack Feingold have emerged, and Gov. Scott Walker built a GOP ground game that Johnson can put to use again in 2016. But the Democrat has outraised Johnson since declaring his candidacy, and the gold-standard Marquette University Law School polls have shown Feingold with even more consistent leads in name identification, favorability, and the head-to-head match-up.

3. New Hampshire — GOP Sen. Kelly Ayotte running for reelection (3)

Sen. Kelly Ayotte is faced with a challenge from Democratic Gov. Maggie Hassan. | Getty

As anticipated, Democratic Gov. Maggie Hassan decided to run against Ayotte. The race was already hot even before Hassan jumped in, with GOP outside groups spending millions attacking her, and both campaigns had already aired radio attack ads by the end of 2015. Both start out popular and closely matched. Keep an eye on Ayotte's efforts to moderate her record, including supporting Obama’s Clean Power Plan, and how they have drawn the ire of conservatives in the state. Some are now attempting to recruit a primary challenger. While no candidate has emerged yet, New Hampshire's late filing deadline and primary give them plenty of time to wreak havoc on Ayotte’s delicately balanced chances this fall.

4. Florida — Open, GOP Sen. Marco Rubio retiring to run for president (5)

Rep. Patrick Murphy, the Democratic establishment's pick, looks stronger than he did three months ago. Democratic Rep. Alan Grayson's senior campaign staff quit, dealing a blow to his insurgent primary challenge, although Florida's late August primary and Grayson's personal wealth give him plenty of opportunity to rebuild. But in the third quarter, Murphy nearly outraised his three major GOP challengers — Reps. Ron DeSantis and David Jolly and Lt. Gov. Carlos Lopez-Cantera — combined. While outgoing Rubio's improved chances in the presidential contest mean the GOP nominee may get a boost, Murphy looks like the strongest candidate in the field at the moment. This race has more time to develop than just about any in the country, though.

5. Pennsylvania — GOP Sen. Pat Toomey running for reelection (6)

Democrats' messy primary here remains just that, with establishment favorite Katie McGinty unable to pull away from former Rep. Joe Sestak before paid-media season, and tattooed Braddock Mayor John Fetterman getting a ton of earned media in the meantime. Establishment Democrats have lined up behind McGinty, but even another big fundraising quarter might just put her and Sestak on equal financial footing heading into 2016 and the April primary. Meanwhile, Toomey has chugged along, with allies hinting at another monster fundraising quarter to add to the $8.6 million he already banked. But Pennsylvania has been consistently blue territory in presidential years, and even a Sestak primary victory, so feared by establishment Democrats, wouldn't guarantee disaster for them. Toomey only beat him by two percentage points in 2010, one of Democrats’ worst elections in recent memory.

6. Nevada — Open, Democratic Sen. Harry Reid retiring (4)

Republicans are overwhelmingly bullish about Rep. Joe Heck, who has spent his congressional career doing the kind of minority outreach party leaders would like everyone to do. Democrats, meanwhile, are practically salivating over Heck’s record and statements on birthright citizenship and Social Security, which they say make him unelectable in a state as blue-trending as Nevada. The GOP wave was particularly fierce there in 2014, but Democrats also feel confident Hispanic voters will line up in a presidential year to elect the nation's first Latina senator in Catherine Cortez Masto. Those state trends may prove more important than either candidate, though there is a recent example to the contrary: Republicans are trying to turn Catherine Cortez Masto into Shelly Berkley 2.0 by criticizing her travel expenses as state attorney general. Berkley’s ethics trouble helped Republican Dean Heller win in 2012 — but only with 46 percent of the vote, and only by a percentage point, illustrating how tough Nevada can be for the GOP.

7. Ohio — GOP Sen. Rob Portman running for reelection (7)

Ohio's contest is eerily similar to Pennsylvania's, featuring a high-fundraising incumbent Republican who broke with the GOP on a major issue — where Toomey backed universal background checks for gun purchasers, Portman supported gay marriage. Meanwhile, Democrats are hoping to follow Obama’s lead after he won the state twice, but they trail in fundraising and have primaries to sort out. Former Gov. Ted Strickland is a big favorite with a name-ID advantage over even Portman, but P.G. Sittenfeld has been a tenacious Democratic challenger, and a pro-Sittenfeld super PAC waits in the wings to cause primary mischief. Strategists can make the case for Ohio, Pennsylvania and Nevada to go in almost any order. Ohio’s pure swing-state status, compared to the other two states’ Democratic leans, might make it a tougher flip in 2016.

8. Colorado — Democratic Sen. Michael Bennet running for reelection (8)

Bennet keeps his edge as the Republican primary field continues to fill out. Republicans in Colorado and Washington like state Rep. Jon Keyser, another in a long string of potential candidates who could keep adding to a big GOP primary. But conservative state Sen. Tim Neville and self-funding businessman Robert Blaha could still stand in the way of an establishment favorite. GOP Sen. Cory Gardner clearing his primary in 2014 was an overlooked but massively important step in his eventual victory, and Republicans don’t appear to have that option in 2016.

9. Missouri — GOP Sen. Roy Blunt running for reelection (10)

Democrats couldn't be much higher on Missouri Secretary of State Jason Kander, a veteran who has gone on the offensive on national security against Blunt. Kander is looking to be the latest statewide Democrat to successfully fight national tides in Missouri, which Mitt Romney easily carried in 2012. Blunt has also dealt with a series of stories looking at his son and campaign manager's lobbying work. Still, the Blunt family has never lost a statewide general election, the incumbent retains a healthy lead in cash on hand, and Missouri isn’t on the presidential battleground map yet.

10. North Carolina — GOP Sen. Richard Burr running for reelection (9)

This seat still leans toward its Republican incumbent, too, even as several Democrats — including former state Rep. Deborah Ross, Spring Lake Mayor Chris Rey and businessman Kevin Griffin — vie to take him on. Burr’s approval ratings may be in the mid-thirties, but the race is much lower on the Democrats’ priority list. A strong financial showing from one of the Democratic challengers in the fourth quarter, or an unexpectedly rough GOP primary from libertarian physician and repeat candidate Greg Brannon, could change the tone, but Burr cruised through 2015.

11. Arizona — GOP Sen. John McCain running for reelection (12)

Democrats are generally pleased with Rep. Ann Kirkpatrick, but she'll need to pick up her fundraising to match McCain's $5 million war chest. She could also hope McCain drains his resources, and his favorability fighting off a more serious primary challenger than former GOP state Sen. Kelli Ward, a tea party upstart. Democrat Richard Carmona won 48 percent of the vote in the race for an open Senate seat in 2012, running several points ahead of President Barack Obama, and Kirkpatrick made her House career in a GOP-leaning seat. But statewide success in Arizona has eluded Democrats for a decade now, and McCain’s national security credentials could end up being particularly well-suited to 2016.

12. Indiana — Open, GOP Sen. Dan Coats retiring (11)

Former Rep. Baron Hill has done little to excite national Democrats, and his fundraising has been lackluster. His best hope is an ugly GOP primary between Reps. Todd Young and Marlin Stutzman and former state party chair Eric Holcomb, along with a strong performance from Democratic gubernatorial candidate John Gregg in the general election — in other words, the Democratic formula from 2012. Stutzman, meanwhile, has completely abandoned his original consulting team. But even a tea party-affiliated candidate with a campaign in upheaval might be favored to win in red-leaning Indiana.

13. Arkansas — GOP Sen. John Boozman running for reelection (15)

Democratic former U.S. Attorney Conner Eldridge topped Boozman in third quarter fundraising, and national strategists have been less than pleased with Boozman's performance. Eldridge has earned the backing of the Democratic Senatorial Campaign Committee, created some buzz and hopes former first lady Hillary Clinton of Arkansas can lift his fortunes. But don’t forget that Sen. Mark Pryor, a Democrat who started with a strong brand of his own, also lost his reelection by 17 percentage points in 2014.

14. Kentucky — GOP Sen. Rand Paul running for reelection (13)

Former state Auditor Adam Edelen got wiped out in Kentucky’s 2015 state elections, removing Democrats’ greatest potential obstacle to Paul. Even though Paul has stayed in the presidential contest well past the point many Senate strategists would like, he’s looking solid at home right now.

15. Louisiana — Open, GOP Sen. David Vitter retiring (Unranked)

National Republicans spent a few weeks fretting when it appeared Vitter might run for reelection after getting badly tarnished in a losing gubernatorial run. Vitter instead announced his retirement, freeing up a slew of fresh GOP candidates to get in the race. Four are already running: Reps. Charles Boustany and John Fleming, former Rep. Joseph Cao, and tea party favorite Rob Maness. Gov.-elect John Bel Edwards’s lightning-in-a-bottle win gave hope to dispirited Democrats in the state, but no one has stepped forward for the Senate yet.

Theodoric Meyer and Elena Schneider contributed to this report.

Visit the Campaign Pro Race Dashboard to track the candidates and consulting firms engaged in the top House, Senate, and gubernatorial races of 2016.