Party conventions in the United States are rallies for the faithful. Three days of speeches and pageantry are crafted to move from one emotional peak to the next, to fire up the troops, and provide the intellectual and policy framework for the campaign that will follow. Putting the conventions back to back makes clear the contrast in the Republican and Democratic parties' messages and focus. But for the Democrats, like the Republicans before them, the key theme is the choice that voters will make in the ballot box in November.

For U.S. President Barack Obama, the Democratic nominee, the message is simple. He urged supporters and undecided voters to give him another term to finish a job not yet complete. He also called on them to embrace his vision of a country that works together as one, in contrast to the GOP depiction of a nation of rugged, self-reliant individualists. The outcome of November's vote is now likely to depend on the ability of each party to rally its faithful. The U.S. electorate continues to be deeply divided, with neither candidate getting much of a bounce from its convention. That means the turnout of the base is key — and a small number of undecided voters in a few swing states will receive unrelenting attention in the remaining nine weeks before the election.

The Democrats certainly rallied the base. Political professionals and pundits alike applauded the passion and power of the leading speakers at the Democratic Party convention. Most agreed that even Mr. Obama, a spellbinding speaker at his best, was eclipsed by the performances of his wife Michelle on the opening night and the nomination speech by former President Bill Clinton on the second night of the conclave. It is no small measure of Mr. Clinton's gifts that more people watched his speech than the season opener of the National Football League, a game that featured two of the most popular teams in the country, one of which, the New York Giants, was last year's Super Bowl champion.