WASHINGTON (AP) - The nation's most influential small business

lobby is joining a court challenge to President Barack Obama's

health care overhaul, arguing that Americans cannot be required

under the Constitution to obtain insurance coverage.

The National Federation of Independent Business will announce

Friday it is joining a federal lawsuit filed in Florida by 20 state

attorneys general and governors, NFIB President Dan Danner said in

an interview. All but one of the state officials are Republicans,

and the case coincides with an election year.

NFIB's involvement ensures that constitutional arguments for

overturning the health care law - even if they fail to sway federal

judges - will be extensively aired in the fall campaigns. With

350,000 members, the group boasts a far-reaching network of local

activists.

Florida Attorney General Bill McCollum, a leader of the legal

challenge and a GOP candidate for governor, said he has "received

a lot of strong response and reaction in support when I have spoken

of this subject. I think voters as a whole are concerned."

A groundswell of opposition to the law from small business

owners prompted NFIB's decision to join the court challenge, said

Karen Harned, a senior lawyer for the group. "The second the law

was signed, NFIB was hearing from its members: 'What are you all

going to do about this?'," said Harned. "So we hunkered down. We

looked around. This state attorneys general lawsuit made the most

sense for us. It's the only one that has a national presence."

The health care law, passed by a Congress divided on partisan

lines, puts the nation on a path to coverage for all. One of its

pillars is the requirement that most Americans carry health

insurance - through an employer, a government program, or by buying

their own policy.

The mandate is effective in 2014, when new competitive insurance

markets open for business. Insurers will then be required to take

all applicants, no longer allowed to turn away those in poor

health. The government will offer tax credits to help middle-class

households pay premiums. And Medicaid will be expanded to cover

millions more low-income people.

Individuals who refuse to get health insurance will be hit with

a tax penalty, although exceptions are allowed for financial

hardship and religious reasons. Businesses will also be required to

contribute to the cost of their workers' health insurance, but

companies with fewer than 50 employees are exempt.

The Obama administration argues that the coverage requirements

rest on a solid constitutional foundation: the power of Congress to

regulate interstate commerce.

But critics say that does not give government the right to

direct individuals to purchase a specific good or service.

The new law allows government "to regulate you just because you

exist," said Danner. "If you can regulate this, where do you

stop? Do you tell people, 'We are going to mandate that everybody

exercise?' We think this is an overreach by the government. It goes

too far, and threatens individual freedom."

The administration counters that a decision to opt out of health

insurance is not merely a matter of personal choice. It has

consequences for others, since uninsured people will get sick, or

have accidents, and someone must pay for their care if they can't

afford it.

"Individual decisions to forgo insurance coverage, in the

aggregate, substantially affect interstate commerce by shifting

costs to health care providers and the public," Justice Department

said this week in legal papers filed in a similar lawsuit in

Michigan.

People who remain uninsured by choice "have not opted out of

health care; they are not passive bystanders divorced from the

health care market," the government continued. "They have made a

choice regarding the method of payment for the services they expect

to receive, no less 'active' than a decision to pay by credit card

rather than by check."

Legal scholars are divided over prospects for the case. Many -

but not all - expect the administration to prevail.

Timothy Jost, a professor at Washington and Lee University law

school in Virginia, said:

"These are not really legal cases - they are political

statements."