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Today is the deadline for most Americans to have ObamaCare insurance beginning Jan. 1, but a series of administration fixes and delays is turning the milestone into a day that for many Americans will underscore the uncertainty about the future of the law.

The original plan was simple -- that Americans who enrolled in ObamaCare, online or otherwise, by Dec. 23 and paid in full would have insurance when coverage kicks in New Year’s Day.

But the disastrous Oct. 1 start for the federal website and some state-run sites -- marked by crashes and the dissemination of incorrect information -- sent President Obama and other top administration officials scrambling to change the law in hopes of bolstering enrollment numbers.

The president has expressed confidence over the past several days that the changes have helped.

On Sunday, he restated his case that ObamaCare is on the right track but urged those who had yet to enroll to do so by Monday.

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    “The law is working,” he said in a statement. “If you don’t have health insurance, go to [the site] right now and sign up. If you do it before December 23rd, you can be covered on the first day of the New Year. … I’m asking you to spread the word about getting covered.”

    Among the first changes for individual insurance was the president’s proposed legislative fix in mid-November, amid the issuing of millions of insurance cancellation notices. Obama gave insurers the option to extend plans to customers for an extra year, even if the plans failed to meet ObamaCare standards.

    "I completely get how upsetting this can be for a lot of Americans," the president said at the time. "Americans whose plans have been canceled can choose to enroll in the same kind of plan."

    However, the move drew sharp criticism from congressional Republicans and other ObamaCare critics.

    "There is no way to fix this," House Speaker John Boehner said. "I am highly skeptical they can do this administratively."

    Last week, administration officials appealed again to insurers, asking them to accept partial payments or backdate policies for those who enroll after Monday -- in hopes that more Americans, not less, would have insurance by Jan. 1.

    They also said the estimated 500,000 who had yet to replace cancelled policies could get bare-bones ones and that roughly 3.9 million lower-income Americans have qualified for ObamaCare through the law's Medicaid expansion -- collectively closing the enrollment gap created by the estimated 4 million to 5 million cancellations.

    The president said Friday that 1 million Americans through the third week in December had enrolled in ObamaCare. It was a sharp increase compared to the mere 365,000 who had enrolled through November 30 and signaled that many of the computer glitches had been fixed. But the number remains far short of the 3.3 million the administration had hoped for prior to the October rollout.

    Still, several underlying problems persist, including the accuracy of the numbers and how many of those enrolled have in fact paid for their policies.

    Such problems could create far more serious consequences in the coming weeks should people who think they have insurance under ObamaCare go to a pharmacy or doctor’s office and find out otherwise.

    In addition, the complexity of the law, including who is exempt from what, will continue to confuse Americans, Robert Moffit, director of The Heritage Foundation's Center for Health Policy Studies, told FoxNews.com on Friday.

    “This whole thing has turned into a rat’s nest of rules and regulations,” he said. “Who would have thought Health and Human Services Secretary Kathleen Sebelius would grant so many hardships? … This administration is under the mindset of how America is supposed to work, which has nothing to do with how it really works.”

    The White House’s ultimate goal is to provide insurance for an estimate 30 million Americans, which includes subsidizing costs for low-income individuals. The deadline to enroll without facing a tax penalty is March 31.

    Capitol Hill Republicans and other ObamaCare critics have tried numerous times to “defund” or replace the law, with the GOP-led House holding at least 40 votes on the issue.

    What Congress and Obama will do when they return to Washington remains unclear.

    The president is committed to getting insurance for the roughly 20 percent of Americans who previously didn’t have coverage, too be sure.

    “Things will get better,” he said last month. “I make no apologies for us taking this on because somebody, sooner or later, had to do it.”

    However, Moffit and others think the president might be forced to except changes from Capitol Hill as Democrats seeking re-election in 2014 need to show voters they can and have fixed the problems.