Baldwin acknowledged that the rollout of the federal healthcare.gov website was botched. But now that 8 million Americans have signed up, she said it's time for Democrats to focus on how the law has made things better - for example, by not allowing insurance companies to deny coverage based on pre-existing conditions.
"There are accomplishments ... that we should be proud of, that we should embrace and make sure that people truly understand them," she said.
Plenty of Americans were frustrated by flaws in the signup process, she added, but "I've never run across a person who said we should do away with insurance reforms."
Health care reform is likely to be a major issue in the November midterm elections. Baldwin predicted that Republicans would campaign on a futile pledge to repeal or defund the law, and she said she was confident Democrats will retain Senate control after the election.
Baldwin, 52, also expressed her support for raising the minimum wage. She said the increase should also be tied to the rate of inflation so Congress doesn't have to revisit the same political battle every 10 years.
Baldwin said she was concerned about the economy's fragile recovery. She said there are 2.7 job seekers for every open job, which was keeping hardworking Americans from providing for the families. She said she was also concerned that America's middle class, once the envy of the world, has been surpassed by that of other industrialized countries.
"When did that happen? Who was asleep at the job?" she said. "I think of the middle class as being the backbone of our democracy and our economy."
Baldwin was asked about Sen. Elizabeth Warren, a fellow Democrat from Massachusetts who sits with her on the Senate Committee on Health, Education, Labor and Pensions. Warren wants to see the student loan rate lowered to keep college affordable.
An audience member at the Marquette University event asked Baldwin whether she would join Warren's effort. Baldwin replied that the government currently makes money off the student loan program, and said it should be a breakeven program instead.
One questioner drew applause when he asked about the growing wealth disparity in the country. He noted that some CEOs make millions of dollars even as their employees make minimum wage and need food stamps to survive.
Baldwin said that has long been an issue of concern for her. She blamed policy decisions for changing the nation's economic system into one that rewards wealth over work. She said the rich get hefty tax breaks when they make millions on investments, while others who earn money through physical and intellectual labor end up paying a higher tax rate.
"I think we have to question a system that works that way," she said.