MILWAUKEE -

Democratic U.S. Senate candidate Tammy Baldwin said she and President Barack Obama will be voices for the people, while their Republican challengers are more interested in serving the wealthy and special interests.

Baldwin spoke Saturday at Obama's rally in Milwaukee.

Baldwin is locked in a tight contest for the state's open Senate seat with Republican former Gov. Tommy Thompson.

The mention of Thompson's name by Baldwin drew a round of boos from thousands of people at the rally. Baldwin said Thompson isn't running to be a voice of the people, but a voice for Thompson.

Thompson was campaigning Saturday in Superior in far northwest Wisconsin and in Hudson in western Wisconsin.

Baldwin also plans to appear with Obama at his final Wisconsin rally on Monday in Madison.