It's not a good sign when you're the leading candidate in the Republican presidential primary race and not a single person shows up to one of your campaign appearances.

Luckily for Mitt Romney, Sunday was April Fools Day, and U.S. Rep. Paul Ryan and Sen. Ron Johnson were just having a little fun with him when they introduced him to an empty room at a campaign appearance in Wauwatosa on Sunday afternoon.

While a packed dining hall of supporters waited upstairs at the Bluemound Gardens Restaurant, the two Wisconsin Republicans had prepared a nearly identical room decorated with campaign signs in a completely vacant downstairs room.

"We didn't get much of a crowd this morning," they told Romney. "It will be OK, it will be OK."

Romney joked that the visual did not look good in front of the TV cameras in the room, so he was relieved to greet his room full of supporters a couple minutes later at a pancake brunch on the upper level of the restaurant.

"Not only did they do that, but they caught it on camera," Romney said. "This is known as forgive, but remember. We're going to remember this."

There was also a bit of joking when Romney referred to Johnson as "Ron" and Ryan as "Paul." Ryan piped up with, "Ron Paul!" to earn a big laugh.

Romney did not join in on the wordplay

"I'm not going to touch it," he laughed.

Related: Video from Romney's stop in Wauwatosa

Beyond the humorous moments, Romney used his Wauwatosa appearance to continue to attack Obama's "government-centered society," in which 38 percent of the American economy is "consumed by the government."

"They're trying to put the government in charge in a way the founders never envisioned," he told the crowd of about 300.

Romney also criticized Obama's health care bill, dubbed "Obamacare" by its detractors, saying Obama cut $500 billion in Medicare funds to pay for the law. He pledged he would put the brakes on the health care reform law in one way or another if he's elected president.

"Hopefully, the court will stop that," he said. "If the court doesn't, I will."

Johnson, a Tea Party favorite who endorsed Romney Sunday morning, said this presidential election is a "huge moment in our country's history." He added that Romney would be the best candidate to lead conservatives in a fight against President Barack Obama's policies.

"I just want to tell every conservative that I have spoken to Mitt, and he is totally committed to saving America," he said.

Romney's visit to the Milwaukee suburb was his fifth appearance in the area in less than 48 hours and it came as recent polls show Romney with a significant lead over his competitors in Tuesday's presidential primary.

Romney and GOP candidates Rick Santorum and Newt Gingrich appeared at a faith-based conference in Waukesha on Saturday. And Saturday night, Santorum and Romney spoke at the Waukesha County GOP Lincoln-Reagan Day Dinner.

While the April Fool's Day prank played on Romney was a focus on his appearance inside the restaurant, outside the establishment Democratic state Sen. Chris Larson said the real joke is being played on voters in Wisconsin and across the country.

"Where Mitt Romney stands is with the one percent and not the middle class, not protecting middle class economic security.... To be clear this is a guy earlier in the week who was joking about closing factories," he said.

Larson also said he found it interesting that Romney is pledging to end Obama's health care law, even though he signed a similar health care overhaul during his time as the governor of Massachusetts. 

"He’s railing on the president for policies that he fully endorsed and implemented in his own state of Massachusetts," Larson said.