WASHINGTON  Like about a dozen other states, Florida is debating a proposed amendment to its state constitution that would try to block, at least symbolically, much of the proposed federal health care overhaul on the grounds that it tramples individual liberty.

But what unites the proposal’s legislative backers is more than ideology. Its 42 co-sponsors, all Republicans, were almost all recipients of outsized campaign contributions from major health care interests, a total of about $765,000 in 2008, according to a new study by the National Institute on Money in State Politics, a nonpartisan group based in Helena, Mont.

It is just one example of how insurance companies, hospitals and other health care interests have been positioning themselves in statehouses around the country to influence the outcome of the proposed health care overhaul. Around the 2008 election, the groups that provide health care contributed about $102 million to state political campaigns across the country, surpassing the $89 million the same donors spent at the federal level, according to the institute.

Any federal legislation is likely to supersede state constitutional amendments. But backers of the state measures say they want to send a message to Congress and also lay groundwork for fights about elements of the health care package that are expected to be left up to the states.