Wendell Potter, former chief spokesman for health insurer Cigna Corp. (CI), describes himself in his twitter bio as a "journalist who spent 20 years undercover as HMO PR flack, now writing all about it."

While Potter chuckles about the line, he is serious about his foray into the U.S. health reform debate, where he is campaigning for a public health-plan option and, with mild delivery and tough words, targeting what he calls "deceptive and dishonest" tactics of a for-profit health insurance industry that's fighting such a plan.

"They will be spending millions and millions of dollars behind the scenes...to gut reform," he said.

Potter, who retired from Cigna in 2008 after 15 years, emerged last month as a former industry insider, testifying before the Senate Commerce Committee that insurers "routinely dump policyholders who are less profitable or get sick," as companies strive to appease Wall Street analysts and investors.

Potter said a trip two years ago to a rural health fair in Wise County, Va., where people waited in animal stalls to receive medical attention, sparked his epiphany about uninsured Americans and an industry where he spent two decades.

"If you go down there you will see this from a different perspective," said Potter, a former newspaper reporter. The statistic about roughly 47 million uninsured Americans "loses the meaning until you look it in the face."

Potter considers a government-sponsored health plan vital to U.S. competitiveness and to the security of some 75 million uninsured or underinsured Americans.

"All of those people are at risk of losing their houses, filing for bankruptcy and being ruined financially," Potter said.

Cigna and the industry are showing restraint in responding to Potter. He said he has heard from no one currently at Cigna, with the exception of a friend, and neither the company nor the industry's trade group has attacked him, although they take exception to his views on the industry and a public plan.

"Healthcare reform is our top priority, and that's what were focusing on," America's Health Insurance Plans spokesman Robert Zirkelbach said.

"We're not taking it personally, we agree with Wendell that we need healthcare reform, so we've been working towards that," Cigna spokesman Christopher Curran said, noting that the industry supports guaranteed, mandated, coverage for all Americans, regardless of pre-existing illness, among other steps.

"With the changes we have already agreed to, we believe that the healthcare system can be transformed without the creation of a new government-run plan, which we believe could have a damaging impact on healthcare cost and quality in our country," Curran said.

Potter said competition from a government plan would pressure private insurers to cut administrative expenses and counter Wall Street pressure that has insurers looking for ways to avoid paying claims. He dismissed warnings about government bureaucrats making medical decisions under a public plan, saying, "[People already] have a corporate bureaucrat between them and their doctor."

Potter acknowledged he was well-paid by Cigna - and said the company got its money's worth. He conceded he sometimes was "blocking the free flow of information" as a "gatekeeper" at the company. Potter, who earlier worked for Humana Inc. (HUM), has been encouraged by most of the responses to his new role, and understands the criticism from those who question his late-career transformation.

"I think many people undergo changes in life and see things differently, and that's what happened to me," he said. Had he not worked in the industry for so long, Potter added, "I wouldn't know what I know now."

-By Dinah Wisenberg Brin, Dow Jones Newswires, 215-656-8285; dinah.brin@dowjones.com