RICHMOND, Va. (AP) -- Gov. Bob McDonnell is warning state legislative negotiators not to expand Medicaid in Virginia without major federal and state cost reductions first.

The negotiators are racing a fast-approaching deadline for a budget compromise.

McDonnell wrote to lead budget negotiators as they wrestled with whether to authorize the governor to expand Medicaid to about 400,000 more uninsured Virginians. The senate wants the move to happen sooner, while the House prefers it later -- if ever.

The governor's letter came a day after his administration received conditional federal approval for several Medicaid reforms, including administrative simplicity, more efficient service delivery and payment, and benefits more comparable to commercial plans.

States have a choice of whether to expand Medicaid as part of the 2010 federal health care reform law.