BOSTON--Key portions of the state's new universal health care law would be delayed or eliminated under a measure passed by the House, but Gov. Michael S. Dukakis has vowed to veto the action.

Massachusetts representatives voted 114-34 yesterday for changes to the health care law, but the proposals may never get as far as the governor's desk because the Senate has consistently supported the landmark package.

The year-old health-care law was touted last year during the Dukakis presidential campaign as the first of its king in the nation, but advocates say the House changes would gut the bill.

There were two key changes, sponsored by state Reps. Frank Wood-ward (D-Walpole) and Peter Forman (R-Plymouth):

A provision under which employers would have to pay $16.80 per employee into a fund to provide health insurance for the unemployed was delayed from January 1990 to January 1992.

A provision requiring employers with six or more workers to provide health care insurance or pay $1680 into a statewide pool and let the state provide the insurance was eliminated.

"This strikes at the heart of the universal health care bill," said Larry Collins of the state Department of Medical Security, which oversees implementation of the new law.

Collins said he hoped the House would recess for the summer before giving the proposals final approval and sending them to the Senate.

"The hostility of this place certainly had its effect," Collins said, referring to the recent budget and tax debates. "We appreciate the support we've had in the Senate and hope it will continue."

Supporters of the health care law said the changes sponsored by Woodward and Forman would actually cost the state money. Delaying the new law might temporarily help small businesses, they said, but would force state taxpayers to continue paying medical costs that no one else will assume.

"What we are considering is legislation to deny benefits to people looking for protection and incur more costs to the commonwealth," said state Rep. John McDonough (D-Boston). McDonough said the changes sought by Forman and Woodward would cost taxpayers $12 million per year.

But Woodward said the potential cost to the state of going forward with universal health care could be far greater.

"The cost of the universal health care plan is really unknown," Woodward said. "I hope we could step back [and] put it off for a couple of years and make a better, more informed decision."

A key issue is whether the $1680 employers put into the state pool would cover the state's costs per person in providing health care insurance. Estimates vary widely. There are an estimated 600,000 citizens in Massachusetts with no health insurance.

"We're killing the promise we made to the uninsured," said state Rep. Sherwood Guernsey (D-Williamstown).

'Mad Rush'

But Forman said the health care law was enacted last year "in a mad rush" to help the Dukakis presidential campaign. He said the state should know the costs before implementing the bill.

Collins noted that other provisions of the health care law would be unaffected by yesterday's House action.

A "Common Health" program that serves 16,000 disabled children and adults as well as welfare recipients starting new jobs is up and running, he said. Beginning in September, full-time college students will have access to health insurance under the state law. And by this fall, six phased-in programs will begin to provide some 15,000 workers with health insurance through their employers.

Business associations including the Massachusetts Restaurant Association and the National Federation of Independent Businesses lobbied for the changes approved by the House.