Washington State Attorney General Rob McKenna is joining several other Republican AGs in protesting a special deal for Nebraska that was inserted in the Senate health care bill.

That provision reportedly was added to win the support of Nebraska Sen. Ben Nelson, a Democrat viewed as a crucial 60th vote. Under the deal, Washington and other states would have to pay for part of a Medicaid expansion to cover health care for poor families. But Nebraska's tab would be picked up entirely by the feds.

In an interview today, McKenna said he believes that provision could violate Article 1, Section 8 of the U.S. Constitution, which says Congress may collect taxes for the "general welfare" of the U.S., not for a special benefit for a particular state.

"We think it’s constitutionally defective. We’re continuing to research it," McKenna said. And apart from the legality, "it just doesn't seem right," he added.

McKenna said he was asked to join in a possible challenge to "the Nebraska purchase" by South Carolina Attorney General Henry McMaster.

Their counterparts in Alabama, Colorado, Michigan, North Dakota and Texas - all Republicans - have also protested the Nebraska deal.

McKenna's objections with the health-care bill don't end with the Nebraska provision.

He said he may also look into whether it would be constitutional for the federal government to require all U.S. residents to purchase health insurance.

McKenna said that mandate may violate the 10th Amendment, which limits the powers of the federal government - reserving other powers for the states.

"The U.S. government has never before required the citizens of the U.S. to buy a particular good or service," McKenna said. He stopped short of saying he'd launch a legal challenge on that basis. "We need to do more work on it," he said.

And generally, McKenna said he believes health insurance coverage could be expanded by reducing burdensome state regulations that drive up costs and prevent portable policies from being offered across state lines.

"We act as though the insurance companies are acting in a free market environment, but they are not," McKenna said.