Republican governors from Medicaid expansion states oppose a bill to repeal and partially replace Obamacare, saying it would make them pay more for Medicaid.

The letter from the governors of Arkansas, Michigan, Nevada and Ohio puts more pressure on GOP leadership as it tries to advance the bill to the House floor next week. Conservative House and Senate members want Obamacare’s Medicaid expansion to end next year instead of in 2020, but any attempts to change it could create a backlash.