MADISON, Wis. -- Madison Mayor Dave Cieslewicz says the city will vigorously fight a lawsuit challenging its plan to increase the minimum wage.

The state has had the authority to set the minimum wage for the last 90 years. Now, Madison wants that power.

A host of state organizations representing businesses large and small filed a lawsuit this week, asking for a temporary injunction to halt the plan from going into effect Jan. 1, 2005.

"Our members would not be surprised to see this city council decide to secede from the state of Wisconsin and create its own currency," said Doug Johnson of the Wisconsin Merchants Association, which represents 6,000 merchants statewide.

Cieslewicz said he's disappointed by the lawsuit, but "I'm sure it's even more disappointing to the hard-working families who would benefit from the minimum wage ordinance."

The Madison City Council agreed in March to raise the minimum wage for most workers. It would happen in phases -- from $5.15 per hour to $7.75 per hour by Jan. 1, 2008.