Wisconsin Gov. Scott Walker speaks to guests at the Iowa Freedom Summit on Jan. 24, 2015 in Des Moines, Iowa. (Scott Olson/Getty Images)

The rapid rise of Wisconsin Gov. Scott Walker as a top-tier contender for the Republican presidential nomination in 2016 is one of the more surprising stories of the opening months of this year. Whether he was prepared for this sudden emergence is an open question.

The second-term governor is in an unusual position today. Only a few months ago, his prospects of winning the Republican nomination were judged somewhat equivocally. Today he is touted in the media and Republican circles as a serious long-distance runner in the presidential marathon.

At the same time, for all the attention his clashes with public employee unions have generated, he remains a politician barely known to the public at large. A recent series of Quinnipiac University polls in Colorado, Iowa and Virginia found that Walker had “the lowest name recognition” of any candidates tested.

That means most Americans will begin to form their impressions of Walker over the coming months — and why each small moment of exposure has the potential for exaggerated impact on his political future. Walker says he is not worried about the exposure, having weathered difficult moments over the past four years.

Walker has come charging out aggressively onto the national stage this winter. He has projected supreme self-confidence. “I would just tell you one thing,” he said three weeks ago to Martha Raddatz, ABC’s chief global affairs correspondent, on the network’s “This Week” program. “After three elections for governor in four years in a state that hasn’t gone Republican since 1984 for president, I wouldn’t bet against me on anything.”

Like many Republicans of his generation, his political touchstone is former president Ronald Reagan. He and his wife were married on Reagan’s birthday, and he sometimes talks about himself in Reaganesque terms. He has equated his confrontations with organized labor with Reagan’s decision early in his presidency to fire striking air-traffic controllers.

That action by Reagan, he said, sent a signal of firmness and resolve to adversaries around the world, including in the Kremlin. What he has done in Wisconsin, he suggested, should send a similar signal of firm leadership to those who wonder what he would be like as president.

One difference is that Reagan responded after air-traffic controllers had walked off their jobs. They challenged him. Walker deliberately picked his fight with the unions and was caught somewhat by surprise when his move to restrict collective bargaining rights erupted into protests that have kept Wisconsin in a state of political polarization around Walker ever since.

Walker is correct in saying the unions twice since have tried to oust him from office, first in a recall election in 2012 and again in the fall. His victories in those hard-fought and costly elections have set him on a path he hopes will lead to the presidency.

Those labor battles were the first impressions many Americans formed of Walker and are likely the longest lasting. This year there have been other incidents that are beginning to flesh out his profile.

In contrast to the way former Florida governor Jeb Bush has said he hopes to campaign this year — joyfully is the word he uses; positively is how others portray it — Walker begins the long campaign offering a different profile, one of no compromise on conservative principles. He is disciplined in his approach.

Walker gave a barn-burner of a speech to a conservative gathering in Iowa last month that, more than anything this year, has created buzz around his prospective candidacy. Since then, his moments in the spotlight have produced a more mixed record.

It was at a dinner for Walker in New York last week where former New York mayor Rudolph Giuliani claimed that President Obama does not love America. Giuliani has subsequently reiterated that and other statements that have been roundly criticized by people in both parties.

Bush quickly distanced himself from Giuliani’s comments, as did Florida Sen. Marco Rubio, another prospective candidate. Rubio said he doesn’t know why he should have to answer for every comment from another Republican but told WPBF-TV, “I’ll suffice it to say that I believe President Obama loves America. I think his ideas are bad.”

Rather than take issue with the former mayor, Walker has only been willing to say that he himself loves America and that he would let the president speak for himself on the same topic. He did so again on Saturday in an interview with The Washington Post’s Robert Costa and myself.

He went a step further. In light of his comments about whether the president loves America, he was asked in an interview whether he believes Obama, who recently talked about his Christian faith at the National Prayer Breakfast, is a Christian.

“I don’t know,” Walker replied. “I’ve never asked him that either.” Pressed on his answer, he explained, “I’ve actually never talked about it or I haven’t read about that.”

Walker was sharply critical of the question, just as he was critical of the repeated questions he’s been asked in the past few days about what Giuliani said. He called it “silly stuff” and a “classic example of why people hate Washington and increasingly dislike the press.”

Toward the end of the interview, Walker reflected on how things have changed for him because of the attention his speech in Iowa produced. He said it has accelerated interest in his prospective candidacy and has helped to open doors, both to grass-roots support and to potential contributors.

Asked whether it has caused greater scrutiny than he had anticipated at this time, Walker said that, too, has come somewhat faster than expected. In some ways, he said, it has been helpful because it has stirred conservatives to defend him from some of the criticism he’s received.

Walker said Saturday that he is ready for whatever comes his way. “For us, it’s not that we didn’t think it would happen,” he said. “It’s just that it moved the timeline up. It doesn’t shake us. As you’ve seen, things that might shake up other would-be candidates, we’re used to. We just figure a way to turn it on its side.”