If a stranger claiming to be from the government calls to offer you an “Obamacare card” or threatens to throw you in jail unless you buy insurance, hang up the phone. It’s a scam.

Fraudsters are poised to take advantage of widespread confusion over the Affordable Care Act — also known as Obamacare — to steal Americans’ credit cards, Social Security numbers and other personal information, consumer advocates and government officials say.

“This is the huge, new government program. There’s no doubt in my mind that the fraudsters view it as an opportunity to rip people off,” said Lois Greisman, associate director for the Federal Trade Commission’s division of marketing practices.

The FTC already has issued a consumer alert about one telemarketing scheme, in which impostors claiming to be from Medicare told consumers they needed to hand over their personal or financial information in order to continue eligibility because “change is on the horizon.”

But nothing in the Affordable Care Act threatens existing benefits for Medicare enrollees, Greisman said. The official-sounding calls were just a ploy to steal consumers’ identities and money.

The FTC received more than 1,100 complaints about similar scams in May alone.

Another typical rip-off involves fraudsters who contact consumers by phone or e-mail and say, “I’m with Obamacare. I need your information to send you your new Obamacare card,” said John Breyault, vice president of public policy for the National Consumers League, an advocacy group in Washington.

Some scammers try to sell consumers poor coverage or coverage that isn’t even real.

The callers then request bank account routing numbers or credit cards, or ask for cash directly through a wire transfer, he said.

“Scammers usually say you have to join. ‘It’s the law now, so you have to give us money,’ ” Breyault said. “It’s typically using scary language like ‘the government requires you to do this’ or ‘you’re going to lose your benefits unless you send us money.’ ”

Consumer groups first noticed a spike in complaints about Affordable Care Act swindles after Congress passed the 2010 law. Now, as the Oct. 1 deadline to open health-care exchanges approaches, health-care scams are on the rise again.

“We are starting to get a few complaints that people are receiving unsolicited calls that say they can provide insurance,” said Nanci Gonder, spokeswoman for the Missouri Attorney General’s Office.

“We plan to issue some kind of alert in the future to make sure consumers watch for any calls that could be scams, that could be people trying to get their personal or financial information,” Gonder said.

Scammers prey on consumers’ uncertainty about the new law and how it will affect their lives.

A recent Kaiser Health Tracking Poll found that four in 10 Americans didn’t know that the Affordable Care Act remains the law of the land. That ratio was even higher for people earning less than $30,000 a year, 60 percent of whom couldn’t say whether the law was being implemented.

Greisman worries that some scammers will exploit the government’s efforts to better educate consumers by pretending to be certified “navigators.” The administration has announced $54 million in grants for navigator groups, which will be tasked by law to help uninsured Americans sign up for benefits in the exchanges.

All navigators must be impartial, certified and trained, said Richard Olague, spokesman for the federal Centers for Medicare and Medicaid Services. Some states may require fingerprinting or background checks, Olague said. But it isn’t yet clear whether navigators will be allowed to use telemarketing or unsolicited e-mails in their outreach and education efforts.

“What we’re very likely to see is (fake navigators saying), ‘For an upfront fee we can help you,’ but there shouldn’t be an upfront fee, it should be free,” Greisman said.

She said her agency is waiting for the Department of Health and Human Services to finalize rules for the navigators before advising consumers on how best to distinguish real navigators from fake ones.

With less than three months left before exchanges open, the clock is ticking.

“The closer we get to registration in October, the greater the odds that the con artists are going to be looking for weaknesses in the emergent new systems, and they will be probing. And you can bet your bottom dollar that there will be some fresh and interesting new scams,” said James Quiggle, spokesman for the Coalition Against Insurance Fraud, a nonprofit organization based in Washington.

So far, Quiggle’s group has documented swindles related to the Affordable Care Act in at least 25 states. But consumers can easily fight back, he said.

“Simply close the door, or hang up the phone the moment someone starts probing for your sensitive financial information,” he said. “Do not allow them to try to sweet-talk you and engage you because some of these people are very trained and very good at slowly easing you into giving up your information.”

Consumers should report suspected scam artists to the FTC, state insurance departments and state attorneys general.

“That’s the only way these guys will be put out of business,” said Breyault of the National Consumers League.