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In what might be the death knell for ObamaCare's most controversial component -- the individual mandate to buy insurance -- the administration has added a mega-exemption that critics say would allow virtually anybody to skirt the rule.

"This is a huge public policy decision that could affect millions of Americans," House Speaker John Boehner said, adding that the latest change, made ahead of the March 31 enrollment deadline, applies to "essentially everyone."

"The door's wide open," economist Doug Holtz-Eakin, who leads the conservative-leaning American Action Forum, told Fox News. "[The] mandate which they said was absolutely crucial to ObamaCare is falling apart day by day."

The most recent exemption was included in an ObamaCare application document. There already had been 13 distinct exemptions, but this document added one more -- apparently it was added in late December.

The document said that individuals can now qualify for a "hardship exemption" -- meaning they would not have to pay a penalty for not buying insurance -- if they "experienced another hardship in obtaining health insurance."

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The document does not define what "another hardship" means, and suggests the administration might not be a stickler when it comes to proof either. It says anyone seeking this exemption should "submit documentation if possible."

Of all the exemptions created so far, this category appears to be the broadest. Prior exemptions were created for people who are homeless, who filed for bankruptcy, who experienced a fire and who dealt with other financial emergencies. Already, the 13 exemptions previously on the books could apply to millions. Another created in December would give a pass this year to many of those whose policies were canceled due to ObamaCare and who struggled to find an affordable option -- last week, the administration quietly extended that waiver through 2016.

All along, the administration has rejected congressional attempts to officially delay the individual mandate in its entirety. The White House even threatened to veto one such bill.

But the 14 exemptions now on the books raise the question of whether the mandate has been pushed off in all but name.

"There's a real question as to whether the White House just abandoned the individual mandate," Boehner said Thursday. "It just seems they are hoping no one will notice."

Health and Human Services Secretary Kathleen Sebelius defended the "hardship exemptions" during testimony Thursday before a House subcommittee.

"It's been really aimed at people who could not afford coverage one way or the other," she said. She noted that the list includes people who live in states that did not expand eligibility for Medicaid.

But Holtz-Eakin, former director of the Congressional Budget Office under the George W. Bush administration, said that for someone to qualify for the latest waiver, they could simply say they couldn't get through on HealthCare.gov or plans were too expensive or a special condition they have didn't appear to be covered.

As a consequence, he said, there could be "chaos" in the insurance market. Insurance companies, in exchange for taking on older and sicker patients as part of the Affordable Care Act, were counting on millions of young and healthy Americans signing on. The individual mandate -- and the penalty that comes with it -- was supposed to compel people who might not otherwise buy insurance to enter the system.

Now that the mandate is being softened, it's unclear whether insurance companies will have enough of those new customers to keep premiums down for everyone else.

Fox News' Jim Angle contributed to this report.