Young people, single women, gays and lesbians, blacks and Hispanics came out in large numbers and swelled Obama's majority in 2008. He needs them to turn out heavily again. The Obama brain trust could only hope that these people followed the lengthy proceedings at the 5,000 "watch parties" organized by the Democratic Party or by the constituent groups themselves.
But the evidence from polls, and the fact that the Democrats felt they had to make these appeals, suggests that enthusiasm for Obama, except among African-Americans, is lagging behind 2008. Did the convention and Obama's speech rekindle the spark of his first presidential campaign? It doesn't seem likely.
The Democratic Party throughout its history has been a coalition of disparate groups that, at their strongest, add up to a majority. But when the party has to rally them with appeals that turn off moderates and independents, it's hard to get to 50 percent.
Especially when you make unforced errors, like writing a platform that didn't mention God or Jerusalem as the capital of Israel, and then having the oversight corrected to resounding boos on the floor.
Polls tell us that the Obama Democrats were at the cusp between victory and defeat after Mitt Romney's selection of Paul Ryan and before the two conventions began.
Polls next week will tell us where the race is now. Pundits are looking for bounces, but polls conducted over weekends, and especially over the holiday weekend that separated the two conventions, are problematic.
Two events after the Democratic convention threaten to undermine any positive bounce.
One is the unemployment numbers released Friday morning. The unemployment rate is down to 8.1 percent but only because the labor force is shrinking. Fifty-somethings are going on disability, and twenty-somethings are living with their parents.
The other is the devastating portrait of Obama in Bob Woodward's latest book. "Presidents work their will -- or should work their will -- on important matters of national business," Woodward writes. "Obama has not."