HUDSON, N.H. — Former Florida Gov. Jeb Bush yesterday poked fun at Wisconsin Gov. Scott Walker’s declaration that he’s the front-runner in the race for the Republican presidential nomination, as both heavyweights are set to collide in the Granite State for a second straight day today.

“I’m not a candidate. I don’t think — maybe he is — I don’t know. You can’t be a front-runner until you start running,” Bush said after touring Integra Biosciences here yesterday.

Bush’s remarks were in response to Walker’s comments earlier this week to Breitbart News. He said President Obama’s recent criticism of Wisconsin’s so-called “right to work” law “suggests maybe we’re the front-runner if somebody is taking an active interest in what a state governor is doing, particularly in light of the fact that we’re not the only one.”

Bush’s first political visit to New Hampshire in 15 years drew dozens of local and national media. He proclaimed his visit to Integra as “the coolest tour I think I ever had,” but was more circumspect about his prospective White House campaign.

“I’m joyfully pursuing the possibility of this and I will decide at some point, and then I’ll go at it,” he said, ignoring the massive campaign fundraising that’s taking place on his behalf.

In an attempt to portray himself as more electable than his rivals, Bush reiterated his support for mainstreaming illegal immigrants — a stance that has drawn heat from hard-line conservatives in his party.

“The best plan, the most realistic plan, the grown-up plan, once you control the border … is to say, ‘Let these folks achieve, earn legal status,’ ” Bush said during a business roundtable at Integra. “If we just keep people in the shadows, we’re not going to solve our immigration problems.”

Bush also embraced the so-called Common Core State Standards Initiative, which dictates public school education and math requirements. He said the standards are needed and described a scenario where without them, students could receive a high school diploma, yet still fail entrance tests for community colleges.

“Who’s fooling who?” Bush asked. “Do we feel good about this? Are we that concerned about our self-esteem?”

He suggested his position on Common Core may be unpopular among some Republicans, but it’s also more mature, and hence more likely to attract mainstream voters.

“I think you need to be genuine,” said Bush. “You need to have a backbone. You need to be able to persuade people this is a national crisis. … Our country will not be as dynamic as we want it to be until we improve education in this country.”

Walker, meanwhile, began the day with breakfast at Blake’s in Manchester, then met with former Massachusetts Sen. Scott Brown and his wife, TV reporter Gail Huff, at the Red Arrow Diner. He also planned confabs with former New Hampshire Gov. John Sununu, Liberty Republicans and business leaders at the Pease Development Authority.

Today, he is slated to meet just before noon with state party activists at Concord High School — the first public event of his New Hampshire trip.