(CNN) -

Two leading Republicans and top supporters of Mitt Romney offered the candidate some advice Sunday, saying the presumptive GOP presidential nominee had some work to do in strengthening his message.

Indiana Gov. Mitch Daniels, often mentioned as a possible GOP vice presidential pick, told "Fox News Sunday" that Romney needed to offer a bold, affirmative agenda.

"That's the most successful campaign strategy for him," Daniels said." "The American people, I think, will rightly demand to know something more than he's not President Obama."

Daniels added that Romney had work to do in building a consensus across "a broad spectrum of Americans to big changes we need."

It isn't the first time Daniels has offered some tough love for Romney. In April, the governor made headlines when he criticized some of Romney's attack strategies and said the former Massachusetts governor needed to "campaign to govern, not just to win."

"Spend the precious time and dollars explaining what's at stake and a constructive program to make life better," Daniels told The Indianapolis Star. "And as I say, look at everything through the lens of folks who have yet to achieve."

On Sunday, Daniels also said Wisconsin Gov. Scott Walker's survival in a contentious recall effort Tuesday was not a reflection of the Republican Party's standing nationwide.

Democrats led the recall challenge after Walker signed into law last year a measure that curbed collective bargaining rights for most public employees. The controversy quickly snowballed into a massive labor fight that turned the national spotlight onto Wisconsin for more than a year.

"It would be, I think, a huge mistake for Republicans to misread Wisconsin as some kind of great harbinger. I don't see it that way at all," Daniels said. "I mean, there was clearly a threat of 'enough already' vote there that said it is an abuse of the process with all of the recalls. (It's) not even clear that Gov. Romney will be that strong in Wisconsin."

He added: "So he better have an affirmative and constructive message and one of hope. I think that he will, and that's why I think ultimately he'll prevail."

Daniels, who flirted with a presidential bid last year, has forcefully shot down the idea of being Romney's running mate, even saying in April that if he were offered the No. 2 spot, he would demand the candidate chose someone else.

Walker also had some guidance for Romney on Sunday.

"I just hope he takes a page out of President Reagan's playbook in 1980," Walker said on CBS' "Face the Nation."

The governor added he hopes Romney "goes big and he goes bold" and approaches the election as more than just an opportunity to defeat Obama.

"Here in Wisconsin and other swing states, I think that's the key," Walker added. "The 'R' next to the name cannot be just about being Republican. It's got to be about reformer."