New Jersey Gov. Chris Christie addresses the New Jersey Chamber of Commerce 78th annual “Walk to Washington and Congressional Dinner” in Washington on Thursday. (Yuri Gripas/Reuters)

New Jersey Gov. Chris Christie is rapidly losing support among some of his most prominent home-state donors and power brokers, who are either hesitant to back him or shifting allegiance to former Florida governor Jeb Bush.

Bush’s aggressive moves to lock up the Republican Party’s premier fundraisers threaten to undercut the Garden State governor before his expected campaign can get off the ground, while raising questions about how robust of a network of support Christie will be able to muster.

Bush has stopped short of directly confronting Christie by holding a fundraiser on his home turf. But behind the scenes, he has been quietly wooing, via e-mail, a cadre of high-profile Christie backers, including a group that attended a private dinner with Bush at New York’s Union League Club in January.

“I’ve known and admired Jeb for many years and I’m obviously intrigued by his candidacy, or I wouldn’t have had dinner or communicated with him in recent weeks,” said New Jersey State Sen. Joseph M. Kyrillos Jr. (R), who chaired Christie’s 2009 gubernatorial campaign and attended the New York dinner. “Time will tell how things evolve.”

New York Jets owner Woody Johnson, a onetime Christie booster, signaled his support for Bush on Wednesday when he showed up at a fundraiser in Chicago for Bush’s political committees.

Former New Jersey governor Thomas H. Kean Sr., a longtime mentor of Christie who is no longer close to him, said in an interview Thursday that he hasn’t decided whom to back — while offering praise for Bush.

“When [Bush] said he has strong views on issues and won’t change them to win an early primary, it showed me he has real convictions,” Kean said. “The Republican Party in the past has had problems with people who changed their views in order to win a primary, only to have to scramble back in a general election. Voters don’t find that kind of behavior credible.”

Several Bush donors in New Jersey are also in the initial stages of planning an event in the state in March or April, according to several people with knowledge of the discussions. Bush may not attend, but his backers want to demonstrate his New Jersey support.

Several top Christie backers said Thursday that he still has a strong organization of financial heavyweights both in New Jersey and across the country, and they disputed the notion that he is being undercut by Bush.

“We’re doing fine,” said Kenneth G. Langone, the billionaire co-founder of Home Depot, who has pledged to devote substantial resources to advance Christie’s bid. “Everybody I’ve called and asked has said yes.”

Christie allies do not expect that he will be able to come close to matching Bush’s current fundraising spree, which is expected to bring in tens of millions. His team has sought to project a sense of calm as it makes daily calls to donors, arguing that much of the movement toward Bush is coming from loyalists who received appointments in the administrations of his father and brother.

Ray Washburne, the Dallas real estate developer leading the national fundraising push for Christie’s political committee, said there is plenty of room for both of them.

“Jeb has grabbed a good bit of the donor base, no question,” he said. “But there is still a huge amount of the donor base available to get.”

A Christie aide provided a list of two dozen New Jersey major contributors committed to Christie’s new political committee, including investor Finn Wentworth, trucking magnate Jerry Langer and Christie’s brother, Todd.

New Jersey real estate executive Jon Hanson, who served as finance chairman for Christie’s gubernatorial campaigns, said his in-state donor network is “stepping up and contributing.”

“I can see he’s out there doing a good job,” Hanson said of Bush. “But I don’t think that’s going to hinder our ability to raise money for Governor Christie’s PAC.”

Last week, Christie held a fundraiser at the Greenwich, Conn., home of former GOP gubernatorial candidate Thomas C. Foley. In the coming weeks, he is planning to headline finance events in California and Texas.

So far, Christie has been raising money solely for his Leadership Matters for America PAC, which can accept up to $5,000 from individual donors. An affiliated super PAC, which can raise unlimited personal and corporate money, is expected to be launched soon.

Once it is, Langone said he plans to put in significant amounts of money. “Absolutely,” he said. “I’m waiting for it to start.”

But the investor also noted that he would be squarely behind Bush if Christie’s Florida rival emerges victorious out of the GOP primaries.

“If Jeb Bush is the Republican nominee, I will do everything I can to help him get elected,” he said. “Jeb Bush is a good man. My preference is Christie for one reason: As I look at what this country desperately needs, I think he comes closest to giving us everything we need and want.”

The reticence Christie has encountered among prominent party financiers is a sharp contrast with the more than $100 million that the Republican Governors Association brought in under his recent chairmanship. While Christie aides have credited the fundraising haul to his efforts, some RGA donors have privately said their giving was driven more by their interest in supporting various governors up for reelection.

Christie’s difficulty in locking down home-state support comes after his remarks about child vaccinations on a recent trip to London drew a wave of scathing criticism and alarmed some of his supporters. The governor had to make a series of calls to assure contributors that he supports vaccination for diseases such as measles.

Spencer Zwick, Mitt Romney’s finance chairman in 2012, said the attitude of former Christie backers at home is telling.

“Kyrillos is a very good bellwether for what’s happening in New Jersey,” Zwick said of the state senator. “If Christie decides to run, he’s going to need the support from the people closest to him to sustain him until he can get national Republican support.”

Zwick, who has not committed to a 2016 candidate, added, “Personally, I have had my own reservations about what Governor Christie did at a key moment in the last presidential election and let it be known to him and others,” a reference to extensive public praise by Christie of President Obama for the federal response to Hurricane Sandy in the late stages of the campaign. “But I do not believe he had bad intentions and I have moved on.”

Another former Christie ally, New Jersey attorney Lawrence E. Bathgate II, hosted the Jan. 8 dinner in New York to introduce Bush to some of Christie’s top supporters.

Bathgate had been in Christie’s camp for years, but their relationship publicly soured after Christie’s administration pursued a plan to build protective dunes on the state’s coastline where Bathgate has an oceanfront home.

In an interview, though, Bathgate said his reservations about Christie began when he embraced Obama during his visit to the hurricane-battered state. He also expressed concern about more recent events, including the ongoing inquiry into the closing of traffic lanes leading to the George Washington Bridge.

“I know he wanted to work with President Obama on Sandy, but that doesn’t mean you have to put your arm around him and hug him,” said Bathgate, a former finance chairman of the Republican National Committee. “That took the election and Mitt Romney off the front page. Then you see him a couple years later flying around on Jerry Jones’s jet, jumping up and down like he is a seventh grader. He’s going to have to answer for all of that, and for Bridgegate.”