When Wisconsin Governor Scott Walker toured the state on the eve of Tuesday’s Republican presidential primary, he visited many of the same cities and regions where Mitt Romney and Rick Santorum were campaigning.

But Walker scrupulously avoided visiting those communities at the same time as the candidates.

There’s a reason for the embattled governor’s avoidance of the Republicans who would be president. And there’s also a reason why they might want to avoid being seen with him.

The arrival of the Republican presidential campaign in Wisconsin serves to emphasize the governor’s rigid adherence to the dictates of the same corporate donors who have made the Romney, Santorum and Newt Gingrich campaigns possible. Indeed, the presidential candidates are going out of their way to remind voters that Scott Walker is the local embodiment of the “Wall Street first” ethos that defines the GOP these days.

That’s a problem for the governor, who wants to appeal to moderate and independent voters in the June 5 recall election that could remove him from office. But that won’t shut up Romney, Santorum and Gingrich. Unlike Ron Paul, who is appealing to independent voters and has not talked much about Walker, Romney and Santorum have talked about almost nothing but Walker as they have appealed to the narrow base of Republican die-hards who will participate in what’s likely to be a low-turnout April 3 primary.

Romney and Santorum think that the way to win Wisconsin’s Republican primary on April 3 is to position themselves as big backers of Governor Scott Walker’s anti-labor agenda.

Romney’s major appearance in the vicinity of the state’s second largest city, Madison, was on Saturday at a suburban call center where Walker backers are trying—in  preparation for the recall race—to identify supporters of the governor. Romney used the event, as he has others across the state, to hail Walker as a "hero."

Santorum, who actually made calls at a Walker office last week, has been even more effusive in his praise of the embattled governor, telling crowds they have to work to prevent the recalls of Walker and Lieutenant Governor Rebecca Kleefisch. "Please continue to lead and defend these two great public officials," he told the crowd in Waukesha County.

But you won’t hear Walker thanking the presidential candidates for their support. Even when the governor is in the vicinity of the GOP contenders—at party functions, for instance—he leaves a good distance between himself and Romney and Santorum. And as the primary approaches, Walker is scheduling himself away from the candidates.

Why? Because the governor recognizes that he is in the fight of his political life, and the last thing he wants is to reemphasize why that fight has developed by appearing with Republican presidential candidates who are highlighting precisely the policies that got Walker in political hot water.

Republican operatives quietly acknowledge that the governor would prefer that the GOP contenders talk about anything but fights with unions—and assaults on collective bargaining rights.

But the candidates are going there—aggressively.

Romney poured money into buying automated "robo-calls," which are going into the homes of Republican, independent and even Democratic homes with anti-union messages. "As you know the fight against big labor led by Gov. Walker isn’t over, here in Wisconsin," say the Romney calls. "I was shocked to find out that Rick Santorum repeatedly supported big labor and joined with liberal Democrats in voting against right-to-work legislation during his time in Washington."

In the "am-too, am-not" debate that characterizes the Republican race, Santorum replies: "Calling Rick Santorum a friend of labor is like calling Mitt Romney a conservative. Neither are true."

There’s a reason why the GOP contenders are stumbling over one another to out-Walker Walker. “Let’s face it, this presidential primary is different from any other because it’s taking the backseat politically to the recall, and it’s completely different," says former state Senator Ted Kanavas, a key Romney backer. "It’s the only state in the union, I can guarantee you, where presidential politics isn’t as important as something else. The recall’s all people are talking about politically."

So the candidates are trying to tap into the energy among conservatives who are focused on the recall race.

To that end, Romney has cut new television advertisements that align his message with that of Walker’s austerity agenda, closing with the former Massachusetts governor declaring: “It’s high time to bring those principles of fiscal responsibility to Washington, D.C.”

Santorum came into Wisconsin sounding the same theme. “Of course I’m looking forward to doing whatever I can (to aid Walker),” he says. “I think we’re going to maybe try to swing by throughout the week one of the call centers here to try to help the governor and his effort. As someone who understands tough political fights and someone who stood up to the establishment as this governor has done, we want to give every bit of support we can to someone who has the courage to confront the tough issues. And it shows you we’re willing to do the same kind of thing in Washington, D.C.”

In a sense, Gingrich is going his opponents one better. When I interviewed Gingrich about Walker, he said he’d be glad to come campaign for the governor—or to stay away, if that would be more helpful. “Scott Walker’s fight in Wisconsin has made him a national leader on issues important to Republicans. Of course I would campaign for him,” the former speaker said. “But I would only do that if he asked me. If he didn’t want supporters coming in from outside the state, I’d respect that.”

For all his bombast, Gingrich is actually the smartest of the Republican contenders—as his comment illustrates.

Walker is in trouble in Wisconsin for a lot of reasons. But above all, there is a sense that he has governed not as a servant of the people of Wisconsin but as an errand boy for billionaire conservative donors such as David and Charles Koch and the national movements they fund. Instead of developing ideas that respond to the ideals and demands of Wisconsinites, Walker’s always rushing off to Washington or New York or Texas or Arizona or Florida to consult with right-wing “think tanks”—and, of course, to collect checks for a campaign that, according to its latest report, took in 61 percent of its money from out of state.

Walker is mounting a multimillion-dollar advertising blitz—funded with all that out-of-state money—to foster the fantasy that he is trying to do right by Wisconsin. The last thing he needs is a bunch of Republican presidential candidates reminding Wisconsinites that their governor is not thinking for himself; he’s parroting the same right-wing groupthink as the GOP presidential candidates. Polls suggest most Americans—including a good many Republicans—recognize that agenda as a sellout to corporate CEOs and Wall Street speculators.

Walker will be a very happy man when the Republicans who would be president exit the state on April 3. And he won’t be inviting any of them—not even Newt Gingrich—back before the recall election.

After the recall election, of course, it will be different. Walker could well have all the time in the world to spend with Romney, Santorum and Gingrich. By that point, however, the Republican contenders might not be that interested in being seen with Walker. It’s not just that governors who are recalled tend to lose a lot of their appeal as political "heroes." It’s also that Walker, in addition to a reelection campaign fund, also has a legal defense fund.

The governor recently hired a pair of top criminal-defense lawyers to help him respond to an investigation that has already yielded multiple felony charges against his aides and campaign contributors, might be carrying a lot more baggage than an election defeat by the time the Republican National Convention rolls around.

John Nichols’s new book on protests and politics is Uprising: How Wisconsin Renewed the Politics of Protest, from Madison to Wall Street, just out from Nation Books. Follow John Nichols on Twitter @NicholsUprising.