Story highlights Insurance company executives say they got calls from White House after speaking out

A trade group leader says the Obama administration "is exerting massive pressure"

A White House spokesman calls the accusation "preposterous and inaccurate"

White House officials have pressured insurance industry executives to keep quiet amid mounting criticism over Obamacare's rollout, insurance industry sources told CNN.

After insurance officials publicly criticized the implementation, White House staffers contacted insurers to express their displeasure, industry insiders said.

Multiple sources declined to speak publicly about the push back because they fear retribution.

But Bob Laszewski, who heads a consulting firm for big insurance companies, did talk on the record.

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"The White House is exerting massive pressure on the industry, including the trade associations, to keep quiet," he said.

Laszewski, who's been a vocal critic of Obamacare, said he's been asked by insurance executives to speak out because they feel defenseless against an administration that is regulating their business -- and a big customer.

Government-backed plans accounted for about half of health care policies last year, a number that is expected to grow over the years.

White House spokesman Jay Carney said the idea that administration officials are trying to silence insurance industry insiders is "preposterous and inaccurate." He added that Laszewski has been a vocal critic of health care reform for two decades.

"Plus, it ignores the fact that every day insurance companies are out talking about the law -- in large part because they are trying to reach millions of new customers who will now have new affordable insurance options available from providers through the new Market Places," Carney said.

Obama and his top advisers have acknowledged problems with the health care website.

On Wednesday, Health and Human Services Secretary Kathleen Sebelius was the latest administration official to apologize for the bungled rollout.

Yet she and other officials continue to argue that once they are fully up and running, the insurance exchanges will benefit Americans.

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But Obama also has been accused of breaking his promise that people who like their current plans can keep them. Insurers have begun discontinuing policies that don't meet Obamacare's beefed up coverage requirements.

Laszewski said insurance company officials are embarrassed that they have to cancel plans and force people into more robust, and possibly more expensive, coverage.

Insurers, he said, warned the White House that the regulations would lead to discontinued policies.

"One of the things I think is clear here is the Obama administration has no trust in anything the health insurance industry is telling them about how to run a health plan," Laszewski said.