He's been touring the state since yesterday. He spoke in Waukesha and Mosinee yesterday and in La Crosse today.
In La Crosse, he said his campaign is the underdog but he expects to come from behind and win.
The state hasn't voted for a Republican for president since Ronald Reagan in 1984.
A poll released Wednesday by WISC-TV in Madison showed McCain trailing Obama by 10 points with a month to go before the election. That was McCain's largest deficit since July when polls also showed the Democratic candidate with a double-digit lead.
Yesterday, he told about 2,500 supporters at a rally outside an airplane hangar at Central Wisconsin Airport in Mosinee that Wisconsin would be tough for him to carry.