Santorum got about half the votes of Democrats who voted in the Michigan GOP primary. So did "Operation Hilarity" have an effect? Maybe not as much as Kos would have liked. Aaron Blake explains at The Washington Post:
Exit polls showed 9 percent of voters identified themselves as Democrats and 12 percent identified themselves as strong opponents of the tea party — a dead giveaway that their sympathies probably don’t lie with the Republican Party.
That’s higher than in any contest in the presidential race so far. And among both of these groups, Santorum did well, taking about half of the vote.
But looking at it another way, that haul isn’t terribly novel.
First, the 9 percent of Democrats voting was just slightly more than it was in 2008. In that election, 7 percent of Republican primary voters self-identified as Democrats, even though there was a Democratic primary held the same day (though it should be noted thatPresident Obama wasn’t on the ballot)
Given that there was no competitive Democratic primary on Tuesday, it’s not surprising that more Democrats would take part in the GOP primary. But the difference isn’t even statistically significant compared to four years ago.
Second, the effort paled in comparison to the last time there was a real campaign to get Democrats to cross over.
While Democrats voting for Santorum comprised roughly 5 percent of the vote on Tuesday, in the 2000 race, Democrats supporting John McCain made up about 14 percent of voters overall.
But the most striking feature of Santorum’s double-header defeat Tuesday was his failure to win a majority of his fellow Catholic faithful, who went for the Mormon Romney by a 6-point margin in both Arizona and Michigan.
In Michigan’s open primary, four in 10 voters were self-described Democrats or independents, and Santorum attracted their votes by a wide margin. That helped to bring him close enough to be able to claim a moral victory. But Santorum lost the two cohorts he ought to have won if he hoped to emerge today as a credible threat to Romney—his fellow Catholics, and another key group in this primary season: voters describing themselves as Republicans.