U.S. President Barack Obama continued to promote his national health-care plan on Saturday, promising to "get this right," while tens of thousands of marchers denounced the proposal outside the U.S. Capitol building in Washington.

President Barack Obama holds health-care reform rally Saturday in Minneapolis. (Haraz N. Ghanbari/Associated Press) The president used his weekly radio address to discuss health care and said that, in any given 10-year period, nearly half of all Americans will find themselves uninsured at some point.

Obama cited U.S. Treasury Department figures indicating that 48 per cent of all U.S. residents under age 65 go without health coverage at least once a decade, on average.

The Treasury figures further suggest that 57 per cent of people under the age of 21 will find themselves without insurance at some point during a 10-year span.

Obama vowed to make sure his plan works, once it clears all the hurdles it faces.

"I intend to be president for a while, and once this bill passes, I own it," he said.

"I'm the one who's going to be held responsible. So I have every incentive to get this right," he said in an excerpt released Saturday from an interview with the TV show 60 Minutes.

Obama went on to say that, "in the United States of America, no one should have to worry that they'll go without health insurance — not for one year, not for one month, not for one day."

Still, opponents converged on the U.S. Capitol to speak out against Obama's plan.

Thousands mass in Washington on Saturday during a taxpayer rally against the Obama administration's plan to reform heath care. (Jose Luis Magana/Associated Press) Decrying what they see as exploding growth in government spending, people chanted "enough, enough" and "we the people" and carried signs that said, among other things, "Obamacare makes me sick."

Richard Brigle, 57, a Vietnam war veteran and former Teamster from Paw Paw, Mich., said health care needs to be reformed, but he dislikes the president's plan.

"My grandkids are going to be paying for this. It's going to cost too much money that we don't have," he said while marching with a cane for support.

In a televised speech to a joint session of Congress on Wednesday evening, Obama said the time for partisan bickering is over.

Obama has made reforming the $2.5-trillion U.S. health-care system a priority in his first year of office.

The U.S. spends more on health care per capita than any other country in the world by far, yet life expectancy is no better than in Cuba.

With files from The Associated Press