President Barack Obama, right, talks with Rep. Barney Frank, D-Mass., after signing a Presidential Memorandum regarding federal benefits and non-discrimination during a ceremony in the Oval Office at the White House Wednesday, June 17, 2009, in Washington. Sen. Joseph Lieberman, I-Conn., is second from left. (AP Photo/Haraz N. Ghanbari)

WASHINGTON -- President Barack Obama made a major political mistake by lying about the details of his health care plan, according to former House Financial Services Committee Chairman Barney Frank (D-Mass.).

"The rollout was so bad, and I was appalled -- I don't understand how the president could have sat there and not been checking on that on a weekly basis," Frank told HuffPost during a July interview. "But frankly, he should never have said as much as he did, that if you like your current health care plan, you can keep it. That wasn't true. And you shouldn't lie to people. And they just lied to people."

Obama has taken significant flak in conservative circles for claiming that his health care overhaul would allow all existing health care plans to continue, when, in fact, new consumer protection standards would require some people to sign up for more comprehensive insurance. The law provides government subsidies to help people of modest means pay for the more robust plans. Frank is a strong supporter of the law, and he has repeatedly defended Obama and his legislative agenda.

"He should have said, 'Look, in some cases the health care plans that you've got are really inadequate, and in your own interests, we're going to change them,'" Frank said. "But that's not what he said."

A recent Kaiser Family Foundation poll found that Obamacare continues to be widely misunderstood, with a majority of Americans unaware that the law allows consumers to choose between different private sector health plans. Lying about how the consumer protection standards would function, Frank said, created an unnecessary circus around a program that would help people get better coverage.