Every four years, political prognosticators focus their attention on a small number of swing states that could decide the presidential election. And every two years, national strategists map out the most competitive senate races that cycle in their efforts to either hold or retake control of Congress' upper chamber.
In 2016, those two maps are nearly identical.
Take the oft-touted wisdom that the road to the White House runs through Ohio, for example. The road to a Democratic Senate is a lot smoother if it includes the Buckeye State as well, where incumbent GOP Sen. Rob Portman is defending his seat. The same is true of Florida, the all-important presidential state where GOP Sen. Marco Rubio is running for reelection.
In fact, of this year's top-tier senate races, almost every single one is in a presidential swing state that will be contested in the race between Democrat Hillary Clinton and Republican Donald Trump. Besides Ohio and Florida, Republican incumbents are defending their turf in New Hampshire (Kelly Ayotte), Wisconsin (Ron Johnson), Pennsylvania (Pat Toomey) and North Carolina (Richard Burr), to name a few. And Republicans' only two real pickup opportunities in 2016 also run straight through top swing states in the Mountain West: retiring Sen. Harry Reid's seat in Nevada, and Sen. Michael Bennet's in Colorado.
Of the senate seats most likely to flip this year, only a handful--like Mark Kirk's seat in Illinois or Dan Coats' in Indiana--are in states that are not considered top presidential swing states.
Contrast this year's map with 2012, where some of the hottest races included Massachusetts, North Dakota and Montana--hardly highly contested states in the presidential race between President Obama and Mitt Romney.
2016 was already set to be a big year for senate races--and that's only become more true with Trump at the top of the Republican ticket. Democrats need either four or five seats to win back control of the Senate, and most political observers expect that if Clinton wins she'll also have a Democratic Senate sworn in next January.
Some of that is the consequence of the Republican wave of 2010: in an off-year election full of anti-Obama sentiment and tea party fervor, Republicans picked up senate seats in places they'd otherwise struggle with (think Illinois or Wisconsin). Now that those races are up again in a presidential year, they'll be just as contested as the presidential race in some of these blue or purple states on the map.
So what does this overlap in key states mean for senate campaigns? There are upsides and downsides, veteran political strategists in both parties say.
For the most part, being a state-level candidate in a presidential swing state means your campaign gets access to all sorts of resources--including a state-of-the-art field operation--that it otherwise wouldn't be able to afford on its own. Presidential campaigns in key states run "coordinated campaigns," which benefit the party's candidates from the presidential level down to state and local offices.
And this year, that's especially true of the Clinton operation, which has already opened dozens of coordinated campaign offices in swing states across the country. Clinton's campaign has already opened 18 coordinated campaign offices in Pennsylvania alone; in Colorado, where Clinton campaigned this week, her team touted the openings of its 12th, 13th and 14th joint field offices across the state.
"There's a huge investment in ground operations generally and in GOTV [get out the vote efforts] in particular," Democratic pollster Mark Mellman said of the Clinton operation. "Those mechanisms are not something any other campaign can readily duplicate, readily afford to duplicate--and it's all there because the presidential campaign needs it."
In addition to sharing office space and knocking on doors for candidates up and down the Democratic ticket, state-level candidates are able to share data with the Clinton campaign as well. And Democratic senate candidates also get the added benefit of more frequent chances to appear with Clinton herself. At a rally on Thursday, for example, Clinton campaigned with Nevada senate candidate Catherine Cortez Masto; she's also appeared recently with Ohio's Ted Strickland and Pennsylvania's Katie McGinty.
For Republicans, it's a different story: Trump's campaign has not put the same kind of premium on a strong field operation that past Republican nominees have, so there's less of a tangible benefit to senate candidates on the ground in key states.
Ryan Williams, a former spokesman for Mitt Romney's 2012 campaign, who now works with a handful of senate races on the map this year, said senate campaigns are forced to be a lot more independent this year when it comes to ground operations.
"Usually what happens in a targeted state, the presidential campaign leads ... so you're going to have the RNC victory effort, you're going to have the presidential campaign and that includes the full staff of the campaign itself and the Senate, gubernatorial campaigns working together," Williams said. "This year, there is no Trump campaign--it doesn't exist. There's minimal staff in the states, they're just starting to hire state directors and the campaign has openly talked about how the RNC is going to handle this effort."
"More so than in previous years, they're running efforts that are really independent of the presidential effort," Williams added of the GOP Senate campaigns.
And given Trump's recent comments about some Senate GOP incumbents--including Kelly Ayotte in New Hampshire and John McCain in Arizona--appearing with their presidential nominee is something many GOP senators are actively avoiding.
Perhaps the biggest downside for senate candidates in presidential swing states is what happens to the airwaves: with all the money and attention flowing to the presidential campaign in top swing states, it can be hard (and expensive) for senate candidates to get their ads on the air and their messages out there.
"It's hard--the honest reality is if yours is the third or fourth, fourth or fifth political ad in a pod there aren't going to be a lot of people watching by the time you get there," Mellman said. "First of all, you have to be more creative because that does help get ads noticed; second of all, you have to be multiplatform."