Milwaukee: US politicians Hillary Clinton and Barack Obama traded fresh attacks on Saturday ahead of Tuesday’s primary in Wisconsin.

Clinton kept up her criticism of Obama for refusing to debate her before the Wisconsin vote. She aired two ads earlier in the week hitting him on the issue.

"There are real differences here that we deserve to explore and the people of Wisconsin deserve to have answers to their questions," the New York senator said in Wisconsin.

Obama rejected Clinton’s criticism that he is all talk and no action, and lacks her substance and experience. The two are scheduled to debate on Thursday in Texas.

"The question is not who has got the policies," Obama said at a rally in Eau Claire, Wisconsin. "The question is who can get them done, who can bring people together."