He made a personal appeal for Iowa voters to back his wife.
"I never ask anybody to vote for Hillary because they supported me. I only ask you to listen to my reasons why I think you should caucus for her," Clinton said, adding that his opinion should matter because "I know what it takes to be president" and "because of the life I've lived since I left office."
He seemed to suggest that the nation needs a return to 1990s sensibilities.
"Here's why I think that she is the person to bring us the right kind of change that we need. First of all, what kind of change do we need? We need to get American back to the future. We need to get America back to the solutions business."
He said his wife has the experience to be president, noting among other things her work as Arkansas' first lady on behalf of school standards, her travels as the nation's first lady to 82 countries and her victory as a Senate candidate in several GOP counties in New York.
Left off his list of Sen. Clinton's experiences: her stewardship of the Clinton administration health care plan that failed in the 1990s.
"You need somebody who is strong, competent, has a good vision and never forgets what it's like to be you," Clinton said. "That's why if we had never spent a year together as husband and wife, I'd be here today."
He pulled a pledge card out of his pocket, held it up to the crowd and asked them to caucus on his wife's behalf Jan. 3.
"The reason I want you to sign one of these cards is because I know her," he said. "I hope you make her the next president because she would be a great president and you would never, ever regret it."