Health Secretary Kathleen Sebelius said Sunday that health care reform would have been "dead on arrival" if the White House had sent a finished proposal to Congress last year.
The secretary also blamed delays in passing the measure on President Barack Obama having to spend "far too much time talking about what's not in the bill" and trying to counter "wild accusations" by Republicans.
Under a new push to get the measure through Congress, Obama set a March 18 deadline for the House to pass the Senate version of the legislation before he leaves on a trip to Asia.
Sebelius said she thought the deadline would hold but indicated the president would not walk away from the key agenda item of his presidency should the House not act by then.
She said Obama still hoped for some Republican votes on the health care bill, "but I'm not sure there will be."
The fundamental conflict, she said, centers on Republican beliefs that "insurance companies should have less regulation than they do now, less consumer protection, less oversight."
Republicans argue that the Obama plan amounts to a government takeover of the U.S. health care industry and would increase an already burgeoning budget deficit.
Another stumbling block for House passage has arisen with renewed objections by Rep. Bart Stupak, D-Mich., over what he sees as federal funding for abortion in the Senate bill. The White House and most of those who support the measure insist that is not true.
Sebelius says "conversations will continue" if necessary to overcome Stupak objections. He has insisted on a House-passed plan that says no health insurance plan receiving federal subsidies can pay for abortion, except under exceptions already allowed by federal law.
Sebelius appeared on NBC's "Meet the Press" and ABC's "This Week".