Santorum campaigns in Wisconsin, wins Louisiana primary - WKOW 27: Madison, WI Breaking News, Weather and Sports

Rick Santorum took on unions during his campaign stop in Wisconsin Saturday, calling them "bullies" as he pledged solidarity with Wisconsin Gov. Scott Walker.

"I know what it's like, you know, to fight the bullies. And there is no tougher bullies than the public employee unions," said Santorum. "And I just want to say to your governor, I am for you, I am behind you, and I'm going to do everything I can."

Santorum also reiterated his challenge to Mitt Romney, his rival for the Republican presidential nomination, to hold a one-on-one debate in key primary states, pointing to the debates held between Barack Obama and Hillary Clinton during 2008 when they were the final contenders for the Democratic nomination

Santorum was declared the winner in the Louisiana primary election Saturday night, almost as soon as polls closed.

Several major news groups made the projection based on exit polls, citing Santorum's lead among voters in all income groups except the very wealthy.

Romney was projected to finish second in Louisiana, with former House of Representatives Speaker Newt Gingrich in third place and Texas Congressman Ron Paul fourth.

Santorum has won 11 states, including several in the deep south, but he still trails Romney by a large margin in the delegate count.