FITCHBURG, Wis. -

Republican presidential candidate Mitt Romney, the frontrunner in the state's primary presidential race, threw his support behind Wisconsin's governor and attacked President Barack Obama on Saturday during a stop in Ftichburg.

Romney, speaking to fewer than 100 of Scott Walker's volunteers at a Fitchburg campaign field office, said the governor's convictions were making a difference in Wisconsin.

"I applaud your governor -- what an extraordinary man," Romney said, adding that he would campaign for Walker if the governor asked. "He has convictions, and his convictions are focused on the interests of the people of Wisconsin."

Walker has said he will not endorse any of the presidential candidates ahead of Tuesday's primary. But U.S. Rep. Paul Ryan, R-Janesville, is on the campaign trail with Romney after endorsing the former Massachusetts governor.

He attended the phone bank meet-and-greet with the candidate, and earlier spoke on Romney's behalf at an event in Waukesha.

"For me and my vote, I think we need to coalesce around the person we think is going to be the best president, is going to be best to deliver on these reforms," Ryan said.

A Marquette University Law School poll showed Romney leading Rick Santorum by 8 percentage points, outside the margin of error. Ron Paul, who spoke on the University of Wisconsin-Madison campus Thursday, and Newt Gingrich, who was also in Waukesha on Saturday, were further behind.

"This is the most important election of your lifetime," Gingrich told the Waukesha crowd. "The re-election of Barack Obama will be a disaster for our children and grandchildren and a disaster for our country."

Gingrich and Romney kept their attacks focused on the president, while Santorum tried again to say Romney lacks the conservative credentials to oppose Obama.

"Romney said he's going to run as a conservative in response to the Etch-A-Sketch scandal," Santorum said, referencing the time when a Romney aide said his candidate's policy positions could change for a general election. "I'm not going to run as a conservative. I am a conservative."

Romney, who leads Santorum by a 2-to-1 margin in the delegate count, said that although he was a long way from clinching the Republican nomination, winning Wisconsin could give him insurmountable momentum.

Outside the campaign field office, more than 100 people gathered. Many booed Romney as he entered the office, then shouted "Recall Walker" until the candidate emerged.

However, there were several Republican supporters who weren't lucky enough to make it inside for the speech.

"I really didn't notice how to get inside," said Connie, a supporter from Verona who declined to give her last name. "I just came down to show some support for conservative thought."

"I'm 100 percent for him. He is so knowledgeable," said another supporter, Ann from Madison. "He has such a broad background of experience. We would be lucky to have a president as qualified as he is."

Reporters were not allowed to ask questions of Romney during his Fitchburg stop. The Romney campaign kicked a number of local reporters out of the field office ahead of the event.

Security was high, with a bomb-sniffing dog used before Romney's speech and a heavy police presence once the candidate's motorcade arrived.

R.T. Rybak, a vice chair for the Democratic National Committee, was also on hand at Saturday's GOP event. He said the Republicans can fight it out now, but Obama will defeat them in the fall.

"What we really want is, I think, is a president that is going to lead us through tough times, as ours has done, and we don't want to go back to the bad old days of George W. Bush," said Rybak.

On Sunday, Romney and Ryan will be holding a town hall meeting at the Marriott Hotel in Middleton.

Meanwhile, Romney challenger Rick Santorum, who was in Platteville Saturday afternoon, will be making four stops across eastern Wisconsin on Sunday, including an evening rally in Green Bay.

Former U.S. House Speaker Newt Gingrich will be appearing on CBS's "Face the Nation" Sunday morning.