CHARLOTTE, N.C. -- Maryland Gov. Martin O'Malley played attack dog for President Obama on Tuesday at the Democratic National Convention, calling Mitt Romney an out-of-touch businessman who hides his money in offshore tax havens, during a prime-time address that drew mixed reviews even from Democrats.

O'Malley called for a civilized debate with Republicans over the best pathway to leading the nation forward but spent much of his speech skewering the GOP presidential candidate.

"Swiss bank accounts never built an American bridge," O'Malley said to widespread applause here, in a jab at Romney's handling of his massive wealth. "Swiss bank accounts don't put cops on the beat or teachers in our classrooms. Swiss bank accounts never created American jobs."

(Read the full text of O'Malley's speech)

Much of the convention's opening night was devoted to framing Romney as unfit to serve in the Oval Office, and O'Malley, who has spent months dismissing the GOP as beholden to extremists, had no reservation carrying that torch.

"Mitt Romney and Paul Ryan now say they want to take America back. And so we ask: Back to what?" O'Malley said. "Back to the failed policies that drove us into a deep recession? Back to the days of record job losses? Back to the days when insurance companies called being a woman a 'pre-existing condition'?"

Democrats had hoped for the Maryland governor to make an articulate assault on the Republican ticket ahead of a kinder, gentler speech by first lady Michelle Obama.

But O'Malley's stilted delivery and clumsy turns of speech drew some harsh criticism from some left-leaning observers.

"10 more minutes of O'Malley and I'll vote for Romney," tweeted Peter Beinart, former editor of the New Republic.

"Whose idea was it to put Martin O'Malley on after Deval Patrick?" wondered Bruce Handy, deputy editor of Vanity Fair. " 'Swiss bank accounts never built a bridge?' Even I'm groaning."

A regular on the Sunday talk show circuit, O'Malley is looking to build his brand beyond the liberal bastion of Maryland, where he maintains strong public approval numbers.

However, the crowd here was noticeably more subdued during O'Malley's remarks than those given by Patrick, the Massachusetts governor, whose fiery delivery animated the crowd just before O'Malley took the stage. Some political pundits suggested O'Malley's speech bordered on wooden, appearing overly scripted at times.

O'Malley used his moment in the limelight to tout his Maryland record, including a public education system ranked by some evaluators as the best in the nation. Pointing to Maryland schools, O'Malley said that now is time for more investment in government programs, even if that means tax increases.

"How much less education would be good for our children?" O'Malley asked. "How many American kids can we no longer afford to feed? Gov. Romney: How many fewer college degrees would make us more competitive as a nation?"

O'Malley will look to gain more traction from the Democratic faithful here this week. He will also address a breakfast of Iowa delegates -- a not-so-subtle reaching out to the host of the first-in-the-nation caucuses.