The Obama administration's insistence on a so-called "public option," or government insurance plan, as a crucial part of a health plan has sparked a heated debate in the country.
Critics argue that the Democratic proposal of a public option would have unfair advantages that would drive private insurers out of business.
Pressed on whether Obama was still behind a "public option", Sebelius said Obama "continues to be very supportive of some options for consumers".
She said a Senate proposal of non-profit insurance co-operatives instead of government insurance could also fulfil the White House goal of creating more competition on insurance.
"I think what's important is choice and competition. And I'm convinced at the end of the day, the plan will have both of those. But that is not the essential element."
Sebelius said the administration's goal was insurance coverage for all Americans, lower costs and tighter rules to make sure insurance companies cannot pick and choose who they cover.
In their campaign against Obama's plan, Republicans have played heavily on fears of a government takeover of the healthcare system.
To ease people's worries, Obama has made a series of public appearances during the past week.
Speaking in Colorado on Saturday, he continued his assault on companies that the White House has painted as being at the root of the country's healthcare problems while defending his proposals to fix the system.
"Insurance companies will no longer be able to ... place an arbitrary cap on the amount of coverage you can receive or charge outrageous out-of-pocket expenses on top of your premiums," Obama told a crowd of about 1,500 people.
"No one in America should go broke because they get sick."
He stressed that a government health insurance programme to compete with private insurers was just a small piece of the $1 trillion package.
"The public option, whether we have it or we don't have it, is not the entirety of healthcare reform. This is just one sliver of it," he said.
"And by the way, it's both the right and the left that have become so fixated on this that they forget everything else."