WASHINGTON — As the battle over the health care law was grinding on — Republicans no closer to victory than when they forced the government shutdown — a different fight was rising on a recent Saturday from inside Sharkey's, a bar near the campus of Virginia Tech, 260 miles away.

Lured by free beer, gift cards and the chance to win an iPad, 100 students heard a pitch from the young staffers of a group named Generation Opportunity: Obamacare is a bad deal and you should opt out.

With enrollment in the insurance marketplaces under way, and tens of millions of taxpayer dollars being spent on a public awareness campaign, critics are aiming a provocative counter effort at a critical population: millennials, age 18 to 29, who may not feel the need or have the money for insurance.

Because if too few young, healthy people sign up, Obamacare will be denied the financial blood to support older, more needy participants. So the race is on for the attention of 2.7 million people deemed necessary to enroll in the first year for Obamacare to be successful.

Generation Opportunity, which formed in 2011 and gets funding in part from the conservative Koch brothers, is about to embark on a tour of 20 college towns nationally, including a Nov. 9 stop at the University of Miami. The pitch is that you shouldn't feel compelled by the government to buy insurance and it may be cheaper outside the marketplaces.

A blueprint for a forthcoming tailgate calls for games such as beer pong and Cornhole, free Taco Bell and beer. Pictures of people signing petitions to opt out would be sent over Twitter, Facebook and Instagram.

The group and more recognizable conservative organizations such as Americans for Prosperity and FreedomWorks show how the fight has shifted from Congress to the grass roots. Young people are among the law's most ardent supporters but at the same time many are unaware of the benefits, providing an opening to critics.

"We're happy to watch the law crumble under its own weight by young people making good decisions," said Evan Feinberg, Generation Opportunity's 29-year-old president. "This is a creepy law."

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Creepiness put this group on the map.

Last month, Generation Opportunity launched two videos featuring "Creepy Uncle Sam," who popped up between a young woman's legs during a gynecological exam, and asked a young man to roll over as he pulled on a surgical glove. The message: The government is messing with your health care.

Generation Opportunity, which has an office in Arlington, Va., and a staff of 30 full-timers, including a field director in Florida, never paid to put the videos on television. But they went viral across YouTube and Facebook, getting 3.5 million unique views in the first week, attracting widespread TV news coverage and a response from President Barack Obama.

"It was a really fun moment for me to be out at a bar in Washington and see people watching Creepy Uncle Sam, laughing about it, sharing it with their friends," said Feinberg, a former Republican aide on Capitol Hill and tea party candidate for Congress in Pennsylvania.

On Tuesday he was sitting at the bar in the Mayflower Hotel in Washington, buzzing with health care statistics and polished talking points. As Feinberg ordered an Oktoberfest beer, the waiter asked for his I.D. and that of the group's 24-year-old communications director, David Pasch, who delighted in the message the scene conveyed.

But a youthful vibe and YouTube smash are no guarantee of success.

The group has a budget of $750,000 for the opt-out campaign, a drop compared with the millions being deployed by advocates. The Creepy Uncle Sam videos have generated attention, but much of it has focused on how the message is misleading. The government is not running the health care plans.

"Some of the tea party's biggest donors, some of the wealthiest men in America, are funding a cynical ad campaign trying to convince young people not to buy health care at all," Obama said in a speech last month. "Now do you think if you get sick or if you get hurt and you get stuck with a massive bill, these same folks are going to help you out?"

Feinberg compared the videos to an attack ad Democrats made as Rep. Paul Ryan, the House Republican budget chairman, engineered a plan to restructure Medicare.

"They're not suggesting Paul Ryan is literally pushing granny off a cliff but trying to make a policy point," he said. "We're trying to make a policy point that Obamacare is creepy and invasive. It's obvious satire."

The group, he insisted, has never suggested people go without insurance, only consider that cheaper coverage may be available outside the marketplaces.

Gail Wilensky, an economist and former director of Medicare and Medicaid under President George H.W. Bush, explained that the health care law pushes up rates for young people in order to make the program more affordable for higher users. The law says the most needy cannot pay more than three times of the least dependent. It should be 5-to-1, she said.

Obamacare offers tax subsidies to offset the cost, though how much depends on what a person earns and may not be available for some plans — for example, a catastrophic care plan in Florida for people under 30. The law also says people who opt out cannot be discriminated against if they want to join later, which may encourage some to simply pay the penalty, which starts at a modest $95 in 2014 but rises.

"Nobody meant to discourage exactly the people they need to get in, the young immortals," Wilensky said. "But they did a whole bunch of things to discourage them. All of these things by themselves are not unreasonable, but when you put them together it can be serious."

The work of Generation Opportunity and other detractors, she said, "could just tilt it even more. Even if their motivations are wrong, what they are suggesting may not be unreasonable. The message of check out and see what the alternatives are is perfectly sound."

Of course, even if people do follow the group's advice and obtain coverage outside a marketplace, they are still fulfilling a goal of health reform, to get as many people as possible insured. People who go outside Obamacare surrender any tax subsidies.

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Fabien Levy, a spokesman for the Department of Health and Human Services, said enthusiasm has been high among young people. "We made quality health coverage affordable and now six in 10 Americans shopping for coverage in the marketplace can get coverage for $100 or less per month. That's a great deal for young adults and all other Americans."

The Obama administration is highlighting success stories in videos, a sign of the stakes. To promote the marketplaces it has enlisted celebrities and the popular website FunnyorDie.com, and partnered with a group called Young Invincibles.

AARP has a campaign to get mothers to pester their children to sign up. And Enroll America, a group working on an awareness campaign, has fanned out across college campuses well ahead of Generation Opportunity.

"We're on the ground every day," said Eric Conrad, a spokesman for Enroll America in Florida. Young people may have heard bad things about the law, he said, "but when they learn about what is available to them, they become interested."

While the fight is on, the early scorecard is not known. The government has declined to release enrollment numbers, saying it will wait until November because information is still coming in.

Feinberg would not cite numbers, either, saying only that "tens of thousands" of people have signed Generation Opportunity's online petition to opt out of Obamacare.

Alex Leary can be reached at leary@tampabay.com. Follow him on Twitter @learyreports.