Supreme Court begins debating sweeping health care law "Rule this thing unconstitutional," says a GOP opponent of the law The Supreme Court should let voters decide, says a Democratic supporter The Supreme Court is poised to offer the final word on the constitutionality of health reform The high-demand hearing had people waiting outside for days to be able to attend Washington (CNN) -- The U.S. Supreme Court on Monday began three days of potentially landmark oral arguments over the constitutionality of the sweeping health care law championed by President Barack Obama, with a majority of justices appearing to reject suggestions they wait another few years before deciding the issues. In one of the most politically charged cases in years, the health care reform case drew people who waited in line starting Friday for the chance to attend, and sparked competing news conferences by supporters and opponents of the 2010 law passed by Democrats over united Republican opposition. The public sessions started Monday with 90 minutes of lively debate on a legally dense, but nonetheless important, question. It boils down to whether the health care law's key provision is a "tax" that could prevent the court from considering the broader constitutional questions. The key provision involved is the "individual mandate" requiring most Americans to purchase some form of health insurance or face a substantial tax penalty. This "gateway" issue could stop the current legal fight in its tracks if the justices think the minimum coverage requirement amounts to a tax. Several of them seemed reluctant Monday to take that route. This not about a tax penalty. The suit challenges the 'must-buy' provision," or required minimum coverage, said Justice Ruth Bader Ginsburg. The 'must-buy' is separate from the tax penalty. However, Justice Samuel Alito and Chief Justice John Roberts suggested this was a tax after all. "The whole point (of the individual mandate) is the collection of taxes" from those who do not comply, said Roberts. Why have a command that is toothless? In an unusual twist, the Obama administration is now siding with the law's opponents and strongly argued the mandate is not a tax. Four mostly liberal members of the court -- including Obama appointees Sonia Sotomayor and Elena Kagan -- were aggressive in saying there was no tax at play here. Citing the Anti-Injunction Act might give the court, particularly conservative members, a way out of deciding the explosive issue in an election year. The majority might conclude the political branches can best resolve the conflicts, at least for now, or that the matter can be handled after the November elections. Some court watchers have called this the health care "sleeper issue" that could potentially delay a decision on the constitutionality of the individual mandate for at least four years. Monday's case was Department of Health & Human Services v. Florida (11-398). Outside the court building Monday, supporters and opponents argued their own views. "Everything this administration has done has moved us in the wrong direction, has created such a high level of uncertainty, reduced the confidence of the American people," said Republican Sen. Ron Johnson of Wisconsin. The Supreme Court has to do the right thing and rule this thing unconstitutional. Democratic Rep. Robert Andrews of New Jersey said the high court should let voters decide through elections, instead of imposing a decision by nine justices. "This court has a long tradition of deferring to the judgment of the voters, and that's what I think they will and should do here," Andrews said, adding that the health care law will "help a lot of people and help our country and that will be a great thing for our future." According to the Supreme Court, 110 members of the public -- almost double the initial estimate -- were admitted to watch Monday's arguments, along with 117 credentialed members of the media.The justices know their eventual rulings could establish profound guidelines on the extent of congressional power and could shake up a presidential election year where health care has become a hot campaign topic. Seats inside the court were scarce, both for interested parties and the public. Because of demand, the court's clerk told representatives from Congress, the Obama administration, the states and the dozens of private advocacy groups to decide among themselves who will attend. Legal sources said those negotiations over the choices turned testy when some officials were not picked. Sen. Max Baucus, D-Montana; Sen. Orrin Hatch, R-Utah; and U.S. Rep. Michele Bachmann, R-Minnesota, said they secured precious seats. Attorney General Eric Holder led the administration contingent. Dueling rallies and protests outside the court added to the charged atmosphere. Others have made quite a trek to be in Washington. I have a son who has Type 1 diabetes and a daughter who has epilepsy. Six lawyers will make their case in what are expected to be free-wheeling question-and-answer sessions characteristic of oral arguments. CNN's Tom Cohen, Paul Courson, Casey Riddle and Greg Clary contributed to this report.