Washington (CNN) - Vice President Joe Biden hits the campaign trail again on Friday.
Biden heads to Milwaukee, Wisconsin, to headline a fundraiser for fellow Democrat Russ Feingold. The three-term senator is up for re-election this year. He'll face off in the general election in November against businessman Ron Johnson, who last month won the Wisconsin Republican party's endorsement, or businessman David Westlake. Those two candidates will face off in the GOP primary held on September 14.
"Feingold's maverick image fits well in his state, but he has never won by a huge margin," says Stuart Rothenberg, publisher and editor of the nonpartisan Rothenberg Political Report.
Rothenberg lists the contest as Democrat favored. Another well respected non-partisan political handicapper, Charlie Cook, lists the seat as safe for the Democrats.
On Monday, Biden was in Chicago, serving as the main attraction at fundraisers for Alexi Giannoulias, the Democratic Senate nominee in Illinois, and Dan Seals, the Democratic nominee for the House seat in Illinois 10th congressional district. Next week he's scheduled to travel to Indiana and Ohio to help raise campaign cash for fellow Democrats.
Next Wednesday President Barack Obama visits southeastern Wisconsin, to discuss the economy. It's not known if Feingold will attend that event. The senator is on the Senate Judiciary Committee, which is holding confirmation hearings next week for the Elena Kagan nomination to the Supreme Court.
–CNN's Frances Sanchez contributed to this report
–Follow Paul Steinhauser on Twitter: @psteinhausercnn