The Democrats had themselves a successful convention — at the price of appearing quite conventional.

The delegates left Denver happy and enthused, believing that the divisive nomination fight was finally behind them. But their star, Barack Obama, on the climactic night of the conclave, gave an acceptance speech that was no match for the keynote address he delivered at the 2004 convention in Boston. Sen. Dick Durbin of Illinois, introducing his colleague again here, said that first one “changed politics in America.”

That is hardly an exaggeration. People were talking about the 2004 speech — with its powerful evocation of a national unity far beyond any partisan differences — for weeks. I long ago lost count of the number of Obama volunteers who said they had signed up to support him after watching that address.

No one is likely to argue that the speech here “changed politics in America.” His jibes at John McCain and George Bush were standard-issue Democratic fare and his recital of a long list of domestic promises could have been delivered by any Democratic nominee from Walter Mondale to John Kerry.

There was no theme music to the speech and really no phrase or sentence that is likely to linger in the memory of any listener. The thing I never expected did in fact occur: Al Gore, the famously wooden former vice president, gave a more lively and convincing speech than Obama did.

If this were just an off night by a speaker we know can soar, it would be no more than a blip on the screen. Obama picked a bad night to be ordinary, given the huge crowd that filled the Denver Broncos stadium and the elaborate Grecian setting constructed for his performance.

But John McCain is hardly a major threat as a speaker, so what’s the difference?

Here’s why I think it matters. One of the major questions about Obama, of whom so little is known, is whether he is really serious about challenging the partisan gridlock in Washington or whether his election would simply bring on the regular wish list of liberal policies.

His Boston speech — and many others early in this campaign — suggested that he was sincere in wanting to tamp down partisanship and would be creative enough to see the need for enlisting bright people from both parties in confronting the nation’s problems.

But the Denver speech, like many others he has given recently, subordinated any talk of fundamental systemic change to a checklist of traditional Democratic programs.

Obama’s disappointing speech also reflected what I had thought was the one conspicuous failure of the convention program — the missed opportunity to introduce the country to others in the younger generation of Democrats than just Obama and his dazzling wife, Michelle.

The convention hall was full of bright, attractive men and women serving as governors or mayors or in other posts. Obama knows many of them from his campaign travels, and he gave the keynote spot to one of them, Virginia’s Mark Warner.

But the prime-time spots on the convention program went to Sen. Ted Kennedy, Sen. Hillary Clinton, former President Bill Clinton and Sen. Joe Biden, the vice presidential candidate. All are comfortably familiar figures to members of my generation, and all are part of a Washington that is hardly the favorite of most voters.

My guess is that an Obama administration, if there is one, would bring a lot of new faces and fresh ideas to the nation’s capital. But by giving such an ordinary speech and filling the TV screen with such familiar faces, Obama missed a chance to signal that such change is his mission.

He is not the first Democrat who has promised a new day. Jimmy Carter and Bill Clinton, in different ways, tried to change Washington, and both wound up frustrated. The status quo forces — the interest groups, many in Congress, and parts of the media — all are powerful.

The only time a new president can really change Washington is when he makes it the central message of his campaign, as Ronald Reagan did in 1980.

Reagan’s skill was his rhetoric; hence the label “The Great Communicator.” After the 2004 Obama speech, Democrats thought they had found one of their own. It’s too bad that fellow didn’t make it to Denver.

David Broder is a columnist for The Washington Post. Readers may contact him at davidbroder