MADISON, Wis. (AP) -

Wisconsin Democrats are joining their rival Republicans' call for University of Wisconsin System officials to freeze tuition.

A Legislative Fiscal Bureau memo released last week shows the system finished the 2012 fiscal year with nearly $650 million in reserves, including $414 million in surplus tuition dollars. Republicans are questioning how the Board of Regents could justify raising tuition for six straight years in light of the massive reserves.

Republicans have vowed to freeze tuition in the upcoming state budget. Democratic legislative leaders, typically among the system's staunchest supports, drafted a letter to system President Kevin Reilly and the board Wednesday calling the surplus unjustifiable and asking the regents to freeze tuition for two years.

A system spokesman says it's difficult to comment because the budget is still in flux.