The poll was conducted between March 19 and 23, a week before the White House declared “mission accomplished” on ObamaCare, so maybe it’s simply missing a recent surge in enthusiasm among lefties. The first rule of ACA polling, though, is that the numbers rarely move much no matter what’s going on with the law. They dipped after the Healthcare.gov Chernobyl in October, they bounced back a bit as sign-ups improved, but overall they’ve been steady at around -10 or -12 for years now. Hard to believe that an enrollment milestone will shift that trend markedly and durably, especially with premiums set to rise this fall.

And if it doesn’t, they’re in trouble. Here’s the split right now among likely voters within the “Rising American Electorate,” a.k.a. the Obama coalition of young adults, minorities, and single women, when they’re asked if they’d be more likely to support a Democratic candidate for Congress or a Republican one:

A huge blue advantage — although, as Greg Sargent points out, it’s not as huge as it used to be. In 2012, Democrats won this group 67/32. Meanwhile, though, among the total electorate of likely voters, the Democratic advantage is just 44/43. How can a giant lead among the “RAE” translate into a statistically insignificant single-point lead overall? This is how:

“Non-RAE,” i.e. Republican, voters are far more likely to turn out than O’s base is. To see this slightly differently, compare likely voters overall to the split among “drop-off voters,” people who voted in 2012 but are disinclined to vote in the midterms:

The enthusiasm to turn out this year just isn’t there, for whatever reason. Maybe it’s standard sixth-year presidential fatigue, maybe it’s discontent with the “progress” achieved in O’s second term (especially progress on the economy and unemployment), maybe it’s something else. The pollster, Stan Greenberg, devotes the rest of his memo to showing how the “RAE” numbers would improve if Democrats ran this summer on pocketbook issues aimed at that group — a minimum wage hike, more child-care leave for working moms, etc, which helps explain why O talking about pay equity for women is the soundbite du jour. Not even Greenberg, though, claims that the right message would stop the GOP from making gains in the Senate. This is about triage, not about fully reversing an unfavorable tide.

Which brings me to a question for political junkies: When was the last time one party or the other was able to steer a midterm campaign around to its preferred agenda in a way that materially affected the outcome on election day without obvious help from major intervening events? What I mean is this. During my adult life, the midterm election results have always been most obviously understood as a reaction to the president or to some momentous political development. The big red wave of ’94 was a reaction to total Democratic control of government, which produced HillaryCare; 1998 was a reaction to impeachment overreach; 2002 was a reaction to 9/11; 2006 was a reaction to Iraq; and the big red wave of 2010 was, once again, a reaction to total Democratic control of government, which produced ObamaCare. Those are simplifications, certainly, but the banner-headline items during each period surely did heavily influence voter preferences. When was the last midterm, though, when — and I realize this is a judgment call to some extent — one party was able to elevate its core agenda items (like the minimum wage) above the din of major events and slow a heavy tide in favor of the other party? Has that ever happened? I realize Democrats need some sort of message for the fall and you can always do worse than economic populism, but what’s the precedent for thinking it might work? The GOP plays the ObamaCare card and Democrats play the “more paid leave for working mothers” card and the GOP ends up with only two Senate seats instead of, say, eight? Or is the point here simply to hold the GOP to six pick-ups instead of seven so that Democrats retain control of the Senate?