More than 80 percent of Democratic voters in the Texas counties where Mrs. Clinton had her largest victory margins went on to vote in the U.S. Senate race, the leading statewide contest on the ballot after the presidential race. By contrast, only 71 percent of voters in Mr. Obama's strongest counties did.There are, obviously, two possible storylines here. #1: Smith is right. Obama is generating a lot of excitement among new voters who might not return to the polls in November if he's not on the ballot. That's bad news if he loses the nomination. #2: Obama might attract a lot of new voters in November, but his coattails will be small because many of these voters don't really care about the Democratic Party. They only care about Obama. That's bad news if he wins the nomination.
In Dallas County, where Mr. Obama got nearly two-thirds of the vote, the falloff was nearly 30 percent.
.... The numbers suggest that many Obama voters were drawn singularly to him and might not return in the fall if he's not the nominee — blunting the flood of new voters who Democrats hope will help revive the party in Texas and sweep it into the White House.
...."To get these people to return to the polls in November, the odds are much better if Barack Obama is the nominee," [Obama volunteer Glenn Smith] said.
I'd have to noodle over this a bit before I came to any firm conclusions about which story is more likely. Maybe both are. But my first guess is that Obama isn't doing a hard sell on the Democratic Party right now because he doesn't have to. He's running in a Democratic primary, after all. However, that will all change when the convention is over, and I imagine that after Labor Day he'll be pretty effective at convincing his fans to vote for downticket Democrats. Off the top of my head, I'd say the DMN analysis is interesting, but probably not worrisome.