Despite opposition from physician groups, a House select committee Tuesday overwhelmingly approved a proposal that would give additional power to nurse practitioners, including allowing them to provide care without doctor supervision. House Republican leaders have pushed the proposal, at least in part because they say it would help address a shortage of primary-care physicians in the state. Senate leaders have shown less enthusiasm, but Tuesday's vote was a milestone for the group of health providers technically known as "advanced registered nurse practitioners," who have long sought more authority.