MADISON, Wis. (AP) – Gov. Scott Walker plans to announce on Wednesday his much-anticipated decision on whether Wisconsin will expand its Medicaid services as allowed under the federal health care overhaul law.  Walker spokesman Cullen Werwie said Tuesday that Walker’s decision would be made public Wednesday.    Republican Assembly Speaker Robin Vos says Walker has not told him what his decision is.  Democrats and a host of health care advocacy groups and others, including Wisconsin hospitals, have been urging Walker to take the expansion.   Six Republican governors have already said they would expand Medicaid as allowed under President Barack Obama’s law.  An estimated 175,000 childless adults in Wisconsin are expected to qualify for Medicaid starting in 2014 under an expansion.