Three in 10 Americans want the healthcare reform individual mandate overturned, a poll found, as the Supreme Court heard arguments on its constitutionality. Twenty-nine percent of adults say they want the individual mandate -- requiring most Americans to carry insurance or pay a penalty -- declared unconstitutional, but want the rest of 2010\'s Patient Protection and Affordable Care Act kept in place, a New York Times/CBS News poll released Monday indicated. Twenty-six percent say they want the court to keep the entire law in place, while 38 percent say they want the court to overturn the entire law, the poll found. The nationwide phone poll of 986 adults, conducted Wednesday through Sunday, has a margin of sampling error of 3 percentage points. A study released Monday by the non-partisan Urban Institute think tank found no more than 7 percent of the U.S. population would be subject to the individual mandate. It said if the individual mandate were imposed today, 93 percent of the non-elderly population and 94 percent of the total population would not be required to purchase insurance they don\'t already have. The individual mandate is at the heart of the healthcare law and has become a central campaign issue among Republican presidential hopefuls. Rick Santorum, a former U.S. senator from Pennsylvania, made an appearance on the Supreme Court steps Monday to campaign against the law -- and blast GOP front-runner Mitt Romney. Santorum told reporters he was \"the only person\" who could repeal \"Obamacare.\" Insurance lobbyists argue the mandate is needed to broaden the risk pool so low-risk healthy people, as well as high-risk or unhealthy people, buy health insurance. But studies suggest the so-called adverse-selection risk of a disproportionally large percentage of high-risk people buying insurance is exaggerated, a Yale Law Journal article suggests. Two of four federal appeals courts have upheld the healthcare law\'s individual mandate, a third court declared it unconstitutional and a fourth said the federal Anti-Injunction Act prevents the issue from being decided until taxpayers actually pay penalties for not having insurance. The Supreme Court heard arguments on the Anti-Injunction Act Monday. The 1867 act says taxpayers may not challenge taxes until they become due. It was designed to make sure the flow of taxes needed to keep the government running was not disrupted by lawsuits. The first penalties for violating the individual mandate take effect in 2014, and they would be paid on federal tax returns starting in April 2015. The justices\' questions suggested they thought the Anti-Injunction Act didn\'t apply and the court should decide the case now rather than wait until the penalties for not having health insurance become due, The Washington Post, The Wall Street Journal and The New York Times reported. The Obama administration and the challengers of the all agree they want the court to decide now, rather than wait. Solicitor General Donald Verrilli, representing the administration, was to argue Tuesday against Paul Clement, representing the 26 U.S. states challenging the law, and Michael Carvin, representing the private challengers. The court set 2 hours for Tuesday\'s oral arguments. The court is to consider Wednesday whether the rest of the healthcare overhaul can remain intact if the insurance mandate is ruled invalid. The law\'s challengers are seeking to void the entire law, while the Obama administration argues most of the law\'s provisions aren\'t connected to the mandate and should remain in place even if the court strikes down the insurance requirement. The court will also consider 26 states\' legal attack against the healthcare law\'s expansion of Medicaid, a federal-state partnership providing healthcare to low-income Americans. Lower courts ruled for the Obama administration on this issue. The Supreme Court is widely expected to announce its ruling in the case by the end of June.