“Unmarried women are a critical opportunity for us, and we learned from Terry McAuliffe’s race in Virginia just how important a factor they are,” said Rep. Steve Israel (D-N.Y.), chairman of the DCCC. But he added, “It’s an opportunity that you cannot take for granted, and that is why we are building our earliest and most aggressive field and targeting program ever.”

But Democrats have their work cut out for them. Not only do unmarried women tend to vote in far smaller numbers during midterm elections, Democrats are lagging in support from that group of voters compared with 2012.

Recent polling by Democratic firm Greenberg Quinlan Rosner showed that just under 60 percent of single women likely to vote in 2014 are backing Democrats. Generally, it is a bad sign for Democrats if they are getting less than two-thirds support among this group, said Erica Seifert, a senior associate at the firm.

“The biggest turnout factor for unmarried women is whether they feel the candidates are speaking to the issues that really matter to them,” Seifert said. “That’s the big thing that we’re watching in 2014, if there is a pocketbook-level economic debate that’s going to bring unmarried women out to vote.”