WASHINGTON (Reuters) - Most Americans back the idea of extending health coverage to their low-income neighbors through the government's Medicaid program, unless it means higher costs for their own state, according to a new poll.

In a survey released on Tuesday by the nonpartisan Kaiser Family Foundation, 67 percent of respondents gave a favorable view of President Barack Obama's healthcare reform provision to "expand the existing Medicaid program to cover more low‐income, uninsured adults."

Support for the idea, which would expand coverage to as many as 16 million uninsured Americans, broke sharply along partisan lines. Nearly nine out of 10 survey participants who said they were Democrats and two‐thirds of independents backed the expansion. Six out of 10 Republican participants said they opposed it.

Support dropped to 49 percent when poll participants were asked whether they would like to see Medicaid expanded in their home states, and a slight majority of 52 percent preferred maintaining the status quo when pollsters suggested an expansion could cost their states more money.

The results of the poll of 1,227 adults, conducted in July, have a 3 percentage point margin of error.

Medicaid, which is jointly funded by the federal and state governments and overseen by Washington, currently covers only narrowly defined groups of poor people in most U.S. states, including parents and pregnant women.

Obama's healthcare law, which was upheld as constitutional last month by the U.S. Supreme Court, would expand Medicaid to cover people with incomes of up to 133 percent of the poverty line. Between 90 percent and 100 percent of the cost of expanded coverage would be borne by the federal government.

The high court ruling gave states the ability to opt out of the Medicaid expansion. Several Republican governors have since vowed to do just that while deriding the plan as a costly expansion of federal bureaucracy.

The governors insist that the expansion will mean higher costs for states and lead to higher taxes or reduced funding for other programs such as education.

Proponents of reform say the Medicaid expansion would ultimately save money for states, while also saving lives by providing access to healthcare for those who need it.