MADISON, Wis. (AP) -- Gov. Scott Walker's health secretary says no decision has been made yet on whether Wisconsin will seek a voluntary expansion of Medicaid services as provided under the federal health care overhaul.

Dennis Smith said Wednesday that answer won't be revealed until Walker introduces his budget in February. The expansion is set to take place in 2014 unless states opt out.

Walker has been critical of the expansion, raising concerns about how much it would cost the state. Smith says the state will pay more for its health care programs under the federal law, but he did not have final estimates.

He says, "Medicaid is unsustainable without reform. Without reform, states really can't expand."

Smith was to testify Thursday before a House subcommittee about uncertainty surrounding the Medicaid expansion.