Clinton's visit to the Democratic stronghold and home city of Walker's challenger, Milwaukee's Mayor Tom Barrett, marks the latest in a string of high-profile Democrats who have campaigned on his behalf in recent days.
Clinton told the crowd at a downtown riverfront park that Tuesday's election is about much more than the state of Wisconsin and what's best for its residents.
He said people nationwide are looking to Wisconsin as an American battleground, and states that are recovering economically have embraced "creative cooperation,'' not "constant conflict,'' a reference to Walker's proposal last year that effectively ended collective bargaining for most state workers. The recall was spurred by anger over that move.
One lone Walker supporter, 59-year-old David Willoughby, held a sign and shouted questions through President Clinton's speech. He was eventually cited with disorderly conduct by Milwaukee police.
Walker campaigned Friday with South Carolina Gov. Nikki Haley, who has called herself a "union buster'' and considers her state's low union membership rate an economic development tool.
Clinton is the biggest Democratic name to visit Wisconsin in the truncated recall campaign. President Barack Obama has kept his distance from the union fight as his own re-election efforts near this fall. Wisconsin, with its 10 electoral votes, is a key part of his path to victory.
Clinton's visit is a nod to the importance of turnout for Democrats in Milwaukee, a stronghold for the party where Barrett must do well in order to win. Clinton was to appear at a morning rally with Barret to encourage voters to cast their ballots early. Friday was the deadline for in-person absentee voting.
Maryland Gov. Martin O'Malley, who chairs the Democratic Governors Association, fired up Democratic volunteers Thursday, May 31st in Madison. His visit came after U.S. Rep. Debbie Wasserman Schultz, head of the Democratic National Committee, made a similar stop Wednesday in Racine.
"We don't want to wake up after this election and say, `If only,''' O'Malley told volunteers. "Now is the time to turn on the afterburners.''
O'Malley said he expected the race to be so close, it could come down to a couple votes in every precinct. A strong voter turnout effort could swing the election by as much as five points, he said.
Walker has been leading in polls released by the Marquette University Law School during the past two weeks. The most recent one released Wednesday, May 30th showed Walker with a seven-point edge. The margin of error is 4.1 percentage points.
The recall election has been unlike anything seen before in Wisconsin, with at least $62 million spent by the candidates and outside groups so far, based on a tally released Thursday by the government watchdog group the Wisconsin Democracy Campaign.
Walker was the top spender at $29 million with Democrats including Barrett spending about $4 million. Outside groups have spent $21 million and issue ad groups that don't have to disclose their spending have put in at least $7.5 million.