If Democrats don't retake the Senate majority this year, they face the prospect of a long winter in the minority, because the 2018 map puts them at a severe disadvantage that could leave them even further from the majority and any pick-up opportunities for the foreseeable future.
Just as this year's Senate field offers ample opportunity for Democrats to pick up seats, the next election is stacked for the Republicans, and the one that follows has limited possibilities for Democratic gains.
Mentioning the 2018 races before the 2016 Iowa caucuses have even transpired can give political operatives some heartburn, even though political planning never really stops.
"We're totally focused on 2016 and protecting our majority, and if that makes life more difficult for Democrats in the future, that's all the better," said Greg Blair, deputy communications director for the National Republican Senatorial Committee.
Working in Democrats' favor this year is a Senate map in which they are only defending 10 seats to the Republicans' 24. Those 10 seats are all in states President Barack Obama won twice, and of the 24 GOP seats, seven are in states Obama won twice, and two are in states he won in 2008 but lost in 2012 (Indiana and North Carolina).
That provides the party opportunities to pick up the five seats needed to win the majority outright — or four if the next president is a Democrat and has a vice president to break a 50-50 tie.
But 2018 is virtually a mirror image of this year's political map, with Democrats defending 25 seats and Republicans eight. "The map's not good for Republicans this year, but it flips and won't be good for Democrats next time around," former Senate Majority Leader Trent Lott, R-Miss., told Roll Call in a recent conversation about how the Senate majority tends to change fairly frequently. Since 1980, there have been nine changes in the majority .
The Democrats facing re-election in 2018 include two independents who caucus with the party — Maine's Angus King and Vermont's Bernard Sanders, bringing the number of Democratic seats up that year to 25. Of those 25, 20 are in states the president won twice.
Looking at those 20 seats a little closer, there is a division between states that are reliably Democratic and those that, even though Obama won them in 2008 and 2012, are competitive. That is particularly the case in a midterm election, when turnout has historically favored Republicans.
Those more competitive states are Wisconsin, Ohio, Pennsylvania, Virginia and Florida.
Democratic members and operatives alike said it was too early to consider any 2018 strategies, particularly owing to the expansive presidential campaign this year.
Sen. Bill Nelson of Florida, a former astronaut who would be in line to chair the Commerce Committee if Democrats take back the majority, said he was running for his 2018 re-election and raising money but held off on any broader observations about the next political cycle. "It's hard to raise money back in a state like mine since it's so critical at the presidential [level]," he said.
Four other Democratic seats are in states the president lost twice — North Dakota, West Virginia, Missouri and Montana. The remaining seat, the one held by Joe Donnelly, is in Indiana, which Obama won in 2008 and lost in 2012. Donnelly got an assist from the flawed campaign of Republican Richard Mourdock, who knocked off incumbent Richard Lugar in the primary before getting mired down in comments he made about abortion and rape.
There is a wild card among the solid Democratic states in 2018, as well. In New Jersey, Sen. Robert Menendez is facing multiple federal corruption charges in a high-profile case in the Garden State. Depending on the outcome of the case, the normal dynamics of that race could be interesting, particularly if Menendez runs for re-election.
Sen. Jon Tester, the Montanan who chairs the Democratic Senatorial Campaign Committee for 2016 and is up for re-election in 2018, didn't want to start handicapping just yet, but sounded a bit of a pessimistic note.
"It's an eon away. I mean, you know, so many things can happen. So much stuff can go on," Tester said Tuesday on his way to vote. "Ultimately I would just tell you that if I think this place becomes more functional, it would be good for the country, and it would be good for everybody that's running in '18. But that ain't probably going to happen."
Of the eight seats Republicans will be defending in 2018, only one, Nevada, is in a state Obama won twice, and the seat is held currently by Dean Heller, who has won four statewide elections — three as secretary of State and one, his Senate seat, in 2012.
The others are in ruby red states like Wyoming, Tennessee, Texas, Nebraska, Utah and Mississippi. And then there is Arizona, a state that hasn't voted for a Democrat for Senate or at the presidential level in more than a generation.
Just as the Democrats are on the hunt for seats this cycle, the 2018 numbers will enable Republicans to spend money to go on offense. The vagaries of the campaign can foil plans, though. This year, Democrats identified Sen. Richard Burr, R-N.C., as an early target. But they failed to land a top recruit, including former Democratic Sen. Kay Hagan, and that race is rated as Leans Republican by the Rothenberg & Gonzales Political Report/Roll Call , a pickup opportunity getting away from them.
The map swings somewhat wildly again for 2020, when Republicans will be defending 22 seats and Democrats only 11. But many of those Republican seats fall in states that are safe bets for the GOP, such as Wyoming, Mississippi and West Virginia. A caveat, though. Theoretically, the politics might be scrambled by whoever the new president is, what's happened in Congress in the intervening years, voter registration trends and the inevitable moving of chess pieces caused by retirements, scandal and other issues no one's thought of yet.
"We’re focused on 2016, but are confident that the Democratic incumbents who face re-election next cycle will continue to serve their states and be well-positioned to maintain the majority we win back this year," said Lauren Passalacqua, the DSCC's national press secretary.
Another factor rooted back in the outcome of 2016: Two senators up in 2018 are running for president: Republican Ted Cruz of Texas and Sanders. If either one is elected, he has the potential to affect that year's midterm races personally.