A small but growing group of lawmakers is pressing for state constitutional amendments that would outlaw any health reform requirements that nearly everyone buy insurance or pay a penalty. Approval of the measures, the lawmakers suggest, would set off a legal battle over the rights of states versus the reach of federal power. So far, the notion has been presented in at least 10 states, and lawmakers in four other states have said they will soon offer similar measures in what has grown into a coordinated effort at resistance.