Costa’s story is a microcosm of the turnout problem that plagued Democrats up and down the 2014 ticket, but it’s particularly troubling for the party because Costa’s district is among the most heavily Latino in the country.

Turnout also plunged in other heavily Latino districts, such as the one where Democratic Rep. Jerry McNerney narrowly won reelection in a California district Obama won by 18 points in 2012. There, turnout was down nearly 47 percent between 2012 and 2014. In the state’s 31st District, Rep.-elect Pete Aguilar, who was the heavy favorite in his race, won by just over 3,000 votes after a 52 percent drop-off of voters from 2012 to 2014. And Rep. Lois Capps, whose district Obama won by 11 points in 2012, won by fewer than 8,000 votes after a 32 percent drop-off.

All of this sets up an uncomfortable conundrum for Democrats: If this is purely a cyclical problem and the presidential race brings Latinos back to the ballot boxes, then their recent woes have little bearing on 2016. But that’s a big “if,” and one that no Democratic presidential candidate will be willing to take as a given.