ABC News' Michael Falcone and Arlette Saenz report:

WILLIAMSBURG, Va. - Fresh off his win in Wisconsin's divisive recall election, GOP Gov. Scott Walker was full of advice for Mitt Romney.

"We had significant swing votes - independents, even some discerning Democrats voting for me because they like someone who was willing to take on the tough issues facing our state," Walker said. "I think those same sorts of voters are voters that Governor Romney at least has a shot with."

But Walker, who was among the dozens of governors who gathered at this weekend's National Governors Association Conference in central Virginia, warned that a win in his Midwestern battleground would not be a slam dunk for Romney.

"Coming into Wisconsin, coming into Iowa, coming into other states like that, for him to do well the 'R' next to his name has to stand more than just for 'Republican' - it has to stand for reformer," Walker said, adding: "If people view him as a reformer, willing to take on both the economic and fiscal crisis our nation faces, I think voters in swing states like Wisconsin will listen."

When asked why voters in his state do not already view Romney as a reformer, Walker told reporters: "I think they don't see a lot right now. I think they need to see more of him."

"They'd also like to hear what he's going to do to tackle the fiscal crisis our country's facing," the Wisconsin Republican said. "The more times he comes to Wisconsin, the more times he comes to swing states like ours and lays that message out the better off we'll be."

Walker was one of several Republican governors who dispensed advice for his party's presidential standard-bearer this weekend. He encouraged Romney to "be most aggressive about" pointing out that President Obama "doesn't have a record to run on."

"If I'm Governor Romney," Walker said, "I keep coming back to saying, 'Mr. President, defend your record and lay out what you're going to do for the future' and keep coming back to what I think most people want to hear which is what are you going to do?"

But after a week when the vitriol of the presidential race spiked as both sides accused the other of peddling lies and distortions, another swing-state governor, Virginia's Bob McDonnell, cautioned Romney not to let the Obama campaign set the terms of the debate.

"Mitt Romney can't - he's not going to - respond to every single lame attack that the Obama administration makes," McDonnell said in interview with ABC News. "If he starts to run down every rabbit hole the Obama administration wants to take him, we're going to be off the message."

McDonnell, whose state is likely to see some of the most intense trench warfare of the campaign, predicted that "voters are going to vote - especially the independents - -they're going to vote on jobs, on spending, on energy and leadership."

In May, McDonnell conceded that Obama's team had a better campaign infrastructure in place in Virginia than Romney.

"The ground game's not there yet," McDonnell said in an editorial board meeting with the Washington Examiner.

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Two months later, McDonnell, who runs a state that then candidate Barack Obama won by about six percentage points four years ago, said he's seen a vast improvement.

"We're there," McDonnell said of the Romney campaign's organization in Virginia. "Mitt Romney's personally made a commitment to come to Virginia on multiple occasions. You've seen him here on regular occasions. We've got great surrogates that are out there speaking for him, so we will not be outmatched on the ground or on the air."

But in the part of the state where this weekend's gathering of governors took place, television ads from both sides were already blanketing the airwaves. In new ads, the Obama campaign has been turning up the volume on their attacks on Romney's record at Bain Capital as well as his offshore investments.

"All these attacks by the president and his campaign really, I think, speak volumes to the lack of leadership on the part of Obama," Iowa Gov. Terry Branstad said in an interview. "I guess that is what I find amazing."

In his state - another important battleground - Branstad said the Romney campaign was "doing really well considering the fact that Obama carried Iowa by a pretty substantial margin last time. The polls show they're basically dead even."

But at least one Republican governor expressed concern that Romney needed to do more to avoid the "distractions" caused by his opponent's calls for him to release additional years of his tax returns.

In comments that drew instant attention, Gov. Robert Bentley, R-Ala., said on Saturday that Romney would be wise to "get them out and just get past that."

"They're doing everything they can to hurt Governor Romney and tax returns will be one of those things," Bentley told ABC News. "So the best thing to do is just get everything out in the open and just say, 'hey I have nothing to hide and I'm going to release my tax returns.'"

Branstad disagreed: "You'll never quiet those people that are attacking," he said.

So did Arizona Gov. Jan Brewer, who has emerged as one of country's most controversial governors for her advocacy of the state's tough immigration law.

"I think this is just a distraction that the Obama campaign is throwing out there," she said. "I think Governor Romney has proven his worth. He is honest and he is upright and he has been successful."

Gov. Mary Fallin, R-Okla., also dismissed this week's attacks from the Obama campaign as "negative petty stuff" and advised Romney to offer voters "reassurance that he's got the leadership talent" to be the next president.

"Campaigns can be very negative and ugly," Fallin said in an interview with ABC News, and the key for Romney, she said, is "keeping focused on the main thing and that is families, their pocketbooks, economic issues."