We've listed the eight states below in descending order, based on the number of competitive contests they'll host, the marquee value of the key candidates and the size of the state's population. Without further delay, let's run down 2016's states to watch.
Florida. No one needs to be reminded that Florida is a crucial battleground state during presidential years; look no further than the state's infamous 2000 recount, which sent George W. Bush over Al Gore to the White House. More recently, Barack Obama barely squeaked out victories there in both 2008 and 2012.
But come 2016, Florida will also play host to a competitive U.S. Senate race --Sen. Marco Rubio is up for re-election -- and possibly two competitive U.S. House races -- with the number of House seats in play potentially rising depending on what happens in an ongoing challenge to the current House district lines.
Still, the presidential contest should dominate the electoral cycle there. The Sunshine State's 29 electoral votes remain as pivotal as ever. "Florida will absolutely be a major battleground state," said University of South Florida political scientist Susan MacManus.
Colorado. In both of his presidential campaigns, Obama successfully targeted Colorado, a state that had gone twice for George W. Bush. His victories also coincided with a run of electoral success for Democrats in the state, including gubernatorial wins in 2006, 2010 and 2014, and U.S. Senate victories by Democrats Mark Udall in 2008 and Michael Bennet in 2010.
But after several cycles in which Colorado Republicans nominated candidates with limited statewide appeal, the GOP mounted a strong comeback in 2014, winning a U.S. Senate seat and seizing control of the state Senate. "The Republicans seem to be coming out of their doldrums," said Colorado State University political scientist John Straayer. "They have an improved ground game, better spirit and will perhaps have better candidates in 2016."
Nevertheless, the Democrats in Colorado as in other states should get a boost from presidential year turnout in 2016, which could prove pivotal in state legislative races. The Colorado House is just a few seats shy of flipping into Republican control. And Bennet's Senate seat will be one of the most hotly contested in the nation. "Bennet's seat will be a must-hold for Democrats in the Senate if they are to have any chance of taking back the majority," said Denver-based pollster Floyd Ciruli.
Nevada. Much like Colorado, Nevada shifted from a Republican state in presidential elections under Bush to a Democratic state under Obama. And even more so than in Colorado, the GOP had a terrific year in Nevada in 2014, winning a blowout gubernatorial race, a sweep in statewide offices, a flipped U.S. House seat and control of the state legislature.
Nevada promises to be a presidential battleground again, and Democratic Senate Minority Leader Harry Reid -- a legendary, powerful and polarizing political figure in the state -- will be up for re-election in 2016, when he'll be 76 years old.
His possible presence on the ballot is a big reason Nevada ranks so high on this list. And Democrats - banking on more favorable turnout patterns in a presidential year, as well as organizational efforts by the vaunted Reid machine -- will be looking to take back the U.S. House seat and legislative chambers the party lost in 2014.
Ohio. Arguably the nation's premier presidential battleground in recent election cycles, Ohio should remain a big one in 2016. Either of two Ohio Republicans -- Gov. John Kasich or Sen. Rob Portman -- could end up on the ticket.
Regardless of whether Portman seeks the highest elected office in the nation, Portman is up for re-election, and Democrats will put up a challenge. The state Democratic bench is thin, but Democratic turnout should rise with the presidential election. Possible Democratic candidates could include former Gov. Ted Strickland, former state Sen. Nina Turner or Richard Cordray, head of the federal Consumer Financial Protection Bureau and a former state attorney general.
Ohio would rate higher on this list if the congressional delegation and state legislature hadn't been redistricted so strongly in the Republicans' favor, leaving little electoral competition.
North Carolina. The GOP made significant gains in North Carolina in 2010 and 2012. Thanks to favorable redistricting, even more GOP gains are likely in 2016. That said, the Republican majority may have overstepped its mandate in enacting a strongly conservative agenda in the past two years, helping the Democrats make minor gains in the state House in 2014 despite the strong national GOP wave. It remains to be seen how much of a comeback Democrats can make based on this sense of discontent.
Gov. Pat McCrory will be up for a second term. He campaigned in 2012 as a pragmatist, but the legislature pursued a more conservative agenda and he acquiesced in many cases, drawing some criticism from moderates. Democrats think they can win back the governorship with the popular state Attorney General Roy Cooper, who has consistently out-performed most other candidates in statewide elections.
The Democrats are also hoping for additional gains in the legislature, but the GOP-tilted lines make a full takeover a longshot. The big contests for 2016 will be the presidential and gubernatorial races.
Wisconsin. The state has not voted Republican for president since Ronald Reagan's re-election in 1984. But the GOP has been strong in recent years, with Gov. Scott Walker winning three gubernatorial races and the party seizing solid control of the legislature.
In the meantime, Republican U.S. Sen. Ron Johnson will be running for his second term. Johnson initially won in the strongly Republican midterm year of 2010, and he is expected to be one of the most at-risk incumbents in the U.S. Senate in the Democrat-friendlier year of 2016. Johnson's race will become a marquee contest nationally if the man he beat -- Democrat Russ Feingold - seeks a rematch.
New Hampshire. A "swingy" state in recent election cycles, New Hampshire has grown accustomed to seeing its two U.S. House seats and the state House flip back and forth between the parties. Democrats have had a slight edge -- winning the two-year governorship for six elections running and winning a hard-fought U.S. Senate race in 2014 -- despite the strong national Republican wave.
Republican Sen. Kelly Ayotte will be up for her first re-election. As the incumbent, she will have the edge. Still, she's expected to get a credible challenge, possibly from Democratic Gov. Maggie Hassan. If Hassan runs, the open gubernatorial seat will, in turn, be up for grabs. Throw in the likelihood of competitive U.S. House races and a fight for control of one or both state legislative chambers and you've got a state that will be in the political spotlight for more than just its first-in-the-nation presidential primary.
Pennsylvania. The Keystone State has voted Democratic for president since 1992. And presidential year turnout "really helps the Democrats if Philly voters come out close to what they did for Obama," said Christopher Borick, a Muhlenberg College political scientist.
In addition to the presidential race, Pennsylvania will also play host to a closely watched U.S. Senate race, as Republican Pat Toomey faces his first re-election. Possible Democratic challengers include former Rep. Joe Sestak, Montgomery County Commissioner Josh Shapiro and Katie McGinty, the incoming chief of staff to Gov.-elect Tom Wolf. At least one U.S. House seat, that of retiring GOP Rep. Mike Fitzpatrick, could also be up for grabs.
But one of the most interesting races in Pennsylvania in 2016 could be the contest for state attorney general. Incumbent Kathleen Kane started out strong but has become highly vulnerable, possibly to the point of not seeking re-election. The GOP, smarting from its gubernatorial loss in 2014, would love to win back the office, though the field of potential Democratic successors is long, including Shapiro, former nominee Jim Eisenhower, ex-Rep. Patrick Murphy and Philadelphia district attorney Seth Williams.
