Yesterday Greg Sargent talked to Democratic pollster Celinda Lake and made a discovery that startles us political obsessives. Lake's firm polled 1,000 "drop-off" voters—people who vote in presidential elections but stay home during midterms—in Colorado, Iowa, Kentucky, Michigan, and North Carolina. (Democrats are increasingly favored in Michigan's Senate race, behind in Kentucky, and tied in the rest.) 

"One of the things that came up," said Lake, "is that these drop-off voters had no idea that control of the Senate was even up for grabs and were even very confused about who controlled it."

This is true for more voters than you'd think. Last year an independent Rasmussen poll found that less than two-thirds of voters know who controls the Senate. It's understandable; it's not like divided control has led to the passage of legislation, or something else worth caring about. Attention on Congress has been highest when Congress has staged a crisis and careened into it.

And this is the point of MoveOn's poll, taken for its "Voters Rising" campaign. The theory is that there are enough voters who basically support the Democrats, but don't know what's at stake, to motivate and elect the party's on-the-edge candidates. The most potent messages for these potential voters, both supported by 71 percent of them: "Republicans will shut down the government again" and "Republicans will cut funding for Head Start and K-12 Education." When told that they could make the difference between keeping the Senate Democratic or letting it fall to Mitch McConnell, 50 percent became "very interested."

When I talked to MoveOn leaders, I wondered if anything could dissuade these voters. How many progressives would stay home, say, because their president was leading new military operations in Iraq?

"There is a deep-seated worry about mission creep," said Ilya Sheyman, MoveOn's executive director. "But progressives aren't isolationists. They're deeply concerned about human rights, and about genocide. And there's some sense that George W. Bush broke this, so as a result of what we've done, we now need to prevent genocide."

And that wasn't how these voters thought, according to MoveOn. They always voted for Democrats. All they needed to be told was how bad Republicans were, and what they stood to gain if Democrats stayed home. MoveOn had seen similar message spike turnout before, as Sasha Issenberg and others had reported, and as MoveOn had learned from targeting its 8 million members in 2012. This is the dream of the final midterm: If Democrats just don't refuse to drop off like they did in 2010, if they show up proportionately, they win.