New Jersey Gov. Chris Christie waves after speaking at the Freedom Summit in Des Moines, Iowa, on Jan. 24. (Jim Young/Reuters)

Less than a year before Iowa’s first-in-the-nation caucuses, it appears that every Republican contender is making a serious play to win the state, setting up what is likely to be one of the most active, competitive campaigns here in recent memory.

Political observers in Iowa say that the field is wide open and that numerous candidates have a legitimate shot to win or do well enough to come out with momentum. That is partly because moderates in the Iowa Republican Party, led by Gov. Terry Branstad, have reasserted themselves into the caucus process after watching social conservatives dominate in 2008 and 2012.

The GOP hopefuls, who at the moment number around two dozen, are already battling one another for supporters and potential staff members amid regular visits to the state.

Sen. Rand Paul (R-Ky.), who is near the top of early polling in the state, campaigned here Friday night and spent Saturday at an Iowa State basketball game, where he met several of the school’s influential boosters.

New Jersey Gov. Chris Christie will speak Monday night to Republicans in Dallas County, one of the state’s fastest-growing suburbs and an area his advisers see as a ripe political target.

U.S. Sen. Rand Paul, R-Ky., speaks during an interview with The Associated Press after speaking at a rally hosted by Liberty Iowa, Friday, Feb. 6, 2015, in Des Moines, Iowa. (Charlie Neibergall/AP)

Unlike Mitt Romney, who took a cautious approach to Iowa four years ago, establishment candidates such as Christie look poised to be all-in this time.

Former Florida governor Jeb Bush, along with Wisconsin Gov. Scott Walker and Sen. Marco Rubio (R-Fla.), plans to speak at a business-oriented forum next month, and Bush has tapped a veteran Iowa-based operative, David Kochel, to serve as his campaign manager, should he formally enter the race.

Christie, meanwhile, has enlisted several Branstad associates for his political team. Jeff ­Boeynik, a Christie adviser in Iowa, said he has encouraged the New Jersey governor to focus on the center-right voters who last year elected Branstad and lifted Joni Ernst (R-Iowa), a favorite of GOP leaders, through a crowded Senate primary.

Christie has also courted Rep. Steve King (R-Iowa), a hard-liner on immigration policy from the state’s rural and deeply conservative northwest region, as part of his push to craft a coalition across Iowa’s Republican spectrum.

King said he appreciated Christie’s appearance last month at a tea party conclave in Des Moines and last year at King’s annual pheasant-hunt fundraiser. “He didn’t have time to actually eat some pheasant, but I’m glad he came,” King said in an interview.

Said Boeynik: “The reality is, as the governor of a large state, Governor Christie can’t pull a Rick Santorum-style 99-county tour of Iowa. That doesn’t mean he can’t play, and Iowa is more open to candidates with strong national appeal.”

Foreshadowing what could become a fierce Christie-Bush competition here, Boeynik was dismissive of Bush. “A Bush hasn’t run here in 11 years,” he said, referring to George W. Bush’s 2004 general-election campaign in the state. “That there is a network waiting to be turned on is a fallacy.”

Doug Gross, a Bush confidant in Iowa, said the elevation of ­Kochel, who advised Romney’s 2012 Iowa campaign, provides Bush with access to the key caucus figures and a steady hand to shepherd him through the state’s labyrinth.

“I wouldn’t undersell the Bush name,” Gross said. “It’s a two-edged sword. Yes, the question of dynasty is there for some people. But it draws real interest to what [Bush] has to say.”

Walker, who has tapped Iowa consultant and former Ernst campaign adviser David Polyansky, is quietly laying the groundwork for a robust Iowa campaign. Last week, he hosted a telephone town hall meeting with caucus-goers and leased an office for his advocacy group in Urbandale.

On the other side of the GOP’s Iowa scramble, the activity is just as frenzied, with prominent conservatives in the state receiving phone calls from possible candidates and nearly daily check-ins from their aides.

“On Thursday morning, I got in my truck at 9:03 a.m. and Ted Cruz’s guy called me to let me know [a reporter] may be calling,” said Sam Clovis, a sometime talk-radio host who ran unsuccessfully for U.S. Senate last year. “I said: ‘Yeah, I like Senator Cruz. I’ll say the right things. Don’t worry.’ ”

The Rev. Michael Demastus of Fort Des Moines Church of Christ has been inundated with requests for meetings and invitations to political junkets. Like Clovis, he is intrigued by Cruz (R-Tex.) but remains uncommitted.

Louisiana Gov. Bobby Jindal recently hosted Demastus at a prayer rally in Baton Rouge, and former Arkansas governor Mike Huckabee traveled through Europe with him and other Iowa religious leaders in the fall.

“It was fun,” Demastus said of his swing with Huckabee through Poland and Britain. “But taking me to Europe doesn’t get you my vote. I still have questions for Mike about Common Core,” a set of national education standards that Huckabee once backed but has since disavowed.

Donald Trump is flirting in Iowa as well. When the developer flew to Des Moines last month to speak at King’s event, he invited Chuck Laudner, who coordinated Santorum’s come-from-behind victory in the state’s 2012 caucuses, to ride with him in his luxury black SUV.

“I had never met him before, but he proved to me that he could be a good candidate,” Laudner said. “We had a 20-minute conversation, but he was very unassuming and only spoke for about five minutes. When he spotted some of his fans at the airport, he made sure to ask the driver to pull over so he could shake their hands and sign pictures.”

The latest poll of Iowa Republicans, conducted by Bloomberg Politics and the Des Moines Register newspaper, showed Walker, boosted by his breakout speech at King’s confab, narrowly leading with 15 percent. Paul was at 14 percent, and Huckabee, who won the 2008 caucuses, was at 10 percent. Christie, Bush, Cruz and former Texas governor Rick Perry were in the single digits.

Paul was in Iowa over the weekend meeting with the college students and foreign policy doves who supported the 2012 Iowa campaign of his father, former congressman Ron Paul (R-Tex.), who finished third in the caucuses. Rand Paul attended the basketball game with Steve Sukup, an agriculture magnate who has signed on with the senator for 2016.

Perry, whose 2012 presidential campaign fizzled, said he is undaunted by his back-of-the-pack showing and remains committed to competing in Iowa, if he runs.

“The boost that you get from doing well in Iowa, that’s the rocket fuel, if you will, that takes you into New Hampshire, and then takes you on into South Carolina,” Perry said. “If you don’t do well in Iowa, I’m not going to say it takes you out of the mix, but it sure digs you a big hole.”

Politicking at the edge of Iowa are lesser-known potential candidates, such as former Hewlett-Packard chief executive Carly Fiorina and Ben Carson, a retired Maryland neurosurgeon. Fiorina has shared her personal cellphone number with Iowa politicos, while Carson enthusiasts frequently distribute bumper stickers and pamphlets about the soft-spoken former Fox News personality at local functions.

“I love calls from Carly because I can see her number,” said Renee Schulte, who was a surrogate for Romney in his past Iowa bids. “The others, the big names, they often call from blocked numbers, which I let go to voice mail.”

John Brabender, a Santorum adviser, said the former senator from Pennsylvania is entrenched in Iowa through Patriot Voices, a grass-roots group he founded after his last run ended. But the sweater vest that Santorum made famous in 2012 is not coming back.

“The sweater vest is staying in the closet,” Brabender said. “He wore it because it was cold, and he doesn’t need to wear a uniform or drive some sort of iconic image to do well.”

Numerous events, along with the sheer number of candidates, mean that the race for Iowa is likely to be long and demanding for Republicans. The first candidate “cattle call” came last month, and several others are planned for the first half of the year. The Iowa Straw Poll, long a source of controversy because of its carnival atmosphere, will be held this summer, although it is unclear how vigorously the candidates will compete in it.

The brewing Republican brawl contrasts with the Democratic contest. Most Iowa Democrats expect former secretary of state Hillary Rodham Clinton to remain the front-runner for the party’s nomination.

On Sunday in Ames, organizers of a movement to draft Sen. Elizabeth Warren (D-Mass.) into the 2016 campaign met at a public library, but few Democrats believe that Warren, a star among progressives, will run.

Vice President Biden, mulling a third run for the presidency, will speak on the economy here Thursday and participate in a round­table talk at a community college.

Former Maryland governor Martin O’Malley (D) has hired Jake Oeth, who worked on a Democratic campaign for U.S. Senate in Iowa last year, and will return to Iowa in March and April to headline Democratic events.

Former senator Jim Webb (D-Va.) is less active. “Will keep you posted when there’s Iowa news. We’re just explorers now, like Ponce de Leon still looking for St. Augustine,” Craig Crawford, a Webb adviser, said in an e-mail.

Sen. Bernard Sanders (I-Vt.) will hold town halls at Drake University and at the University of Iowa this month in between huddles with activists.

“I’m better known in New Hampshire, where I’d start off with much more name recognition, but Iowa’s down-to-earth working people are a lot like Vermont’s,” he said. “The people of Iowa, the people of New Hampshire, they don’t believe in anointments.”