CHARLOTTE, N.C. - Minneapolis Mayor R.T. Rybak used his prime speaking slot at the Democratic National Convention on Tuesday night to make a forceful pitch for President Obama's re-election, telling delegates that "this president delivered for the middle class."

"President Obama earned every gray hair on his head fighting for the middle class. ... Now it is time to stand up America and fight for this man," he said.

The high-profile appearance he earned through six years of playing energetic cheerleader for the president allowed Rybak to demonstrate to some in the crowd that he may be ready to do more than run Minnesota's biggest city.

"I believe R.T. is an up-and-comer in the Democratic Party, and he's shown the leadership that Minnesota politicians have. He makes me damn proud," said former Osseo Mayor John Hall, a delegate.

In his speech, Rybak ran through the litany of what he said Obama had accomplished: The Recovery Act, college loan overhaul, clean energy jobs, exiting Iraq and eliminating Osama bin Laden.

"President Obama did all this and more, in spite of a Republican Party that said its number one goal wasn't to help solve any of these problems. ... They spent eight years creating a colossal mess and the last four doing almost nothing -- except, of course, trying to blame it on President Obama. Hey, pyromaniacs shouldn't blame the firefighter," Rybak said, earning cheers and a few laughs.

That's a reminder some delegates may need. With a still-sagging economy, gridlock in Washington and tight national polling, Democrats started their 2012 convention hoping to recapture the magic that catapulted Obama into office four years ago.

Minnesota delegates said Rybak was a welcome messenger.

"It was absolutely the right thing to do, and he was the right person to do it," delegate Eugene Nichols, a retired 3M employee from Shoreview, said of Rybak's Obama pitch.

As a mayor looking for possible promotion, Rybak had competition from other convention speakers. He was one of eight big-city mayors to address Democrats on Tuesday night, the result of a bumper crop of Democratic mayors and of Obama's need to nail down urban areas.

Before Rybak spoke, Newark, N.J., Mayor Cory Booker brought delegates to their feet and cheering "USA" when he said: "When your country is in a costly war, with our soldiers sacrificing abroad and our nation facing a debt crisis at home, being asked to pay your fair share isn't class warfare -- it's patriotism." As he finished his speech, the hall broke into chants of "Cory! Cory! Cory!"

Rybak was well-received with applause and laughter, but there was no chant of "R.T.!" while he was on stage, except from the Minnesota delegation.

An early backer

Rybak endorsed the then-senator from Illinois back in 2006, even before Obama had announced his first run, becoming the first big-city mayor to do so.

During Tuesday's speech, Rybak recalled campaigning in Buffalo Center, Iowa, population 905, on a cold December morning.

"Back on that cold day in Buffalo Center, I was proud to campaign for Barack Obama. But I'm even prouder today," he said.

Now a Democratic National Committee vice chairman, Rybak has traveled the country to promote the president. Rybak said he is doing what he has always done -- it's just in the public eye more.

Despite adapting comfortably to the shine of the national stage, Rybak demurred on whether his convention speech is a path to greater things.

"I'm living in a great place that I love. I have an amazing job," he said. "I'll wind up doing something else at some point in my life, and I'm in no rush to do that."

Staff writer Kevin Diaz contributed to this report. Rachel E. Stassen-Berger • Twitter: @rachelsb