Wisconsin Gov. Scott Walker (R) is preparing to launch a presidential bid next week. His advisers consider former Florida governor Jeb Bush and Sen. Marco Rubio (Fla.) as his main rivals. (Nicholas Kamm/AFP/Getty Images)

Wisconsin Gov. Scott Walker is poised to become the 15th Republican to declare his presidential bid, with at least one more candidate expected to enter soon after. But at this point, his campaign advisers said this week that they see just two principal rivals for the GOP nomination: former Florida governor Jeb Bush and Sen. Marco Rubio (Fla.).

Walker will make his intentions clear Monday with an announcement and rally in suburban Waukesha County, the heart of Republican territory in Wisconsin. The venue will be the same place where he celebrated his victory in a 2012 recall election, one more indication that he intends to make his battles with public employee unions in the state the centerpiece of his appeal to conservative activists.

Walker has weathered repeated controversies as governor and rocky periods during the past six months as he has prepared to formally join the race. He jumped into the top tier in January with a fiery speech at a GOP gathering in Iowa, but was hurt by a series of missteps and statements. He has faced questions about whether he has changed his positions or tone on immigration, abortion and same-sex marriage. Other Republicans say the momentum he once had has abated.

None of that appears to have unsettled Walker or his advisers. With a super PAC called “Unintimidated” — named for the biographical book Walker published about his battles in Wisconsin — the candidate and his advisers are confident as they look ahead to the campaign.

They consider Walker uniquely equipped among the candidates to appeal across the spectrum of the Republican Party. “There are three legs of the stool,” campaign manager Rick Wiley said in an interview. “We play in all three. Who else does?”

Marco Rubio and Jeb Bush, shown here shaking hands in 2006, are seen by advisers to Wisconsin Gov. Scott Walker as his key rivals in the 2016 race. (Steve Cannon/Associated Press)

Some of Walker’s competitors will no doubt try to prove his team wrong in that.

Tea party activists, Wiley said, like Walker’s fighting style and that he won multiple elections while under siege. His roots as the son of a Baptist minister and his faith give him a reach into the GOP’s social conservative wing.

Beyond that, advisers argued that — as a second-term governor who has raised more than $80 million for his Wisconsin campaigns — Walker has appeal in establishment circles, even if he can’t match Bush’s fundraising prowess.

Walker’s path to victory, as outlined by his closest advisers, is not significantly different from that of his rivals, but his team says the calendar sets up well for him.

Iowa is the key: Walker is leading the polls there and, as a neighboring governor, he has easy access to the state. His advisers expect him to win the Iowa caucuses early next year, and they say he can follow that with top-three finishes in New Hampshire and South Carolina. They also think he can score an early victory in Nevada’s caucuses.

Walker’s advisers doubt that anyone who doesn’t win one of the four early states will move to the heavy schedule of contests in March. They also doubt that anyone will have enough delegates to clinch the nomination by the end of March, and they anticipate that the race will drag on into May before there is a winner.

Wisconsin Gov. Scott Walker is a potential Republican contender for president. Here's his take on border security, tax reform and same-sex marriage, in his own words. (Sarah Parnass/The Washington Post)

The enthusiastic reaction to Walker’s speech at the January GOP forum in Iowa produced some obvious dividends. The sudden and positive attention helped with fundraising and grass-roots organizing. But the scrutiny that came with it, compounded by Walker’s wobbly handling of various issues, brought the team its first crisis.

At the time, Walker was just beginning to build his campaign. He lacked the infrastructure to deal with the self-inflicted wounds. “None of our senior staff had even been to Madison,” Wiley said. “It’s amazing we survived.”

The small team stepped up its recruiting and brought on policy advisers who could provide Walker with briefings to become more fluent in key issues. By the end of March, the campaign decided to scale back. For the next month or so, Walker made few public appearances, concentrating on policy briefings and fundraising meetings.

“We had to slow it down,” Wiley said.

Walker formed his first committee last winter, a “527” that allowed him to raise money but did not advocate directly for him as a candidate. The super PAC was formed in April. Walker has held at least 30 meetings with prospective donors since then, said longtime adviser Keith Gilkes, who heads the super PAC.

The combined take for the two committees during the first six months of the year is expected to top $20 million when reports are issued later this month. The super PAC has commitments for an additional $5 million or so, Gilkes said, and hopes to raise at least $20 million by the end of the year, giving it $40 million to start with in 2016.

Walker advisers said his past battles in Wisconsin have given him the kind of grass-roots foundation that no other candidate can match. He has a list of 300,000 or so donors, and his super PAC had more than 200 donors as of a few weeks ago. Walker advisers said they think that is smaller than Bush’s super PAC but larger than those of most of the other candidates.

Beyond that, advisers said, Walker has a list of e-mail addresses that numbers about 700,000. One adviser said that is substantially more than Mitt Romney had by the time he had wrapped up the 2012 GOP nomination.

Walker has come under fresh criticism recently for changing his position on immigration — he once supported a path to citizenship for those here illegally — and for changing his tone, if not his position, on same-sex marriage and abortion.

Gilkes said Walker has not changed his stance on those two issues, although he suggested that the governor’s priorities are more fiscal and economic than social. “His beliefs never change,” he said.

Another adviser said Walker’s call for a constitutional amendment to give states the right to define marriage would end up being a plus, saying Rubio and Bush probably hurt themselves among social conservatives by not reacting more vigorously to last month’s Supreme Court decision that legalized same-sex marriage.

Walker advisers discount possible threats from others in the establishment wing such as Ohio Gov. John Kasich and New Jersey Gov. Chris Christie. Nor do they see a major threat yet in Iowa from those competing hardest for the social and religious conservatives.

“My feeling is every single one of the candidates is focused on Walker in Iowa,” Gilkes said. “I don’t think that’s ever going to let up.”

Walker’s team has conducted two focus groups in Iowa. It has concluded that, although he is not well known, the governor has significant opportunities to expand his appeal. The focus group was shown various videos about Walker and were receptive to the portrayal of his record in Wisconsin. “We have so much to work with,” Wiley said.

For months, Walker’s team has been preparing for a race against Bush’s money and Rubio’s compelling personal story. Advisers said Walker’s record as governor is more current than Bush’s and draws a sharper contrast with President Obama. Rubio has attributes that Walker has spoken about favorably in private conversations, but the governor’s campaign advisers consider the first-term senator far less tested.

Walker’s announcement tour will take him from Wisconsin to Nevada, South Carolina, New Hampshire and then back to Iowa for several days of campaigning. In New Hampshire, he will hold one town hall meeting. He will return to that state later in the month for an event that includes a Harley-Davidson motorcycle ride.

His announcement speech will focus heavily on his record in Wisconsin, reprising his fights with unions. As for his promise to put forth “big and bold” ideas, one adviser said not to expect that in the announcement. Any such policies will be introduced later in the year.