Gov. Bill Haslam of Tennessee said Wednesday that he would not expand Medicaid in his state as called for in the federal health care overhaul, joining 18 other Republican governors who have rejected expansion for now.

Governor Haslam said he wanted instead to use federal Medicaid money to buy private insurance for as many as 175,000 low-income residents of his state. But he said that plan was being held up because the Obama administration had put too many conditions on the money.

With his health care law, President Obama wanted to make Medicaid, the federal-state health program for poor people, available to many more Americans, covering those earning up to 138 percent of the federal poverty level (currently up to $15,856 a year for an individual). But when the Supreme Court upheld the law last year, it ruled that states could opt out of the Medicaid expansion.

For states that opt in, the federal government will pay the full cost of expansion from 2014 to 2016, with its share gradually decreasing to 90 percent in 2020. So far, about two dozen governors, most of them Democrats, have said they want to expand Medicaid.