WASHINGTON – Jeb Bush’s increasingly serious and public examination of a run for president is roiling the ranks of establishment Republican donors and fundraisers who had planned to back Gov. Chris Christie of New Jersey in 2016, forcing many of them to rethink their allegiance to the embattled governor.

In private conversations that are now seeping into public view, some of them are signaling to Christie’s camp that, should Bush enter the race, their first loyalty would be to him, not to Christie, according to interviews with more than two dozen of them.

Many of those who, because of geography and personal ties, were expected to line up behind Christie, say they now feel torn. And it is clear that Christie’s recent troubles, especially the George Washington Bridge scandal, are adding to the allure of Bush, a former Florida governor.

Lawrence E. Bathgate II, a former finance chairman of the Republican National Committee and a major donor in New Jersey, said he dreaded the prospect of having to choose between the two men, calling it “a fraught decision.”

David V. Hedley, a former Wall Street executive and GOP fundraiser in New Jersey, said that he felt tugged in two directions and that “it’s tough right now for me.” Christine Todd Whitman, a former GOP governor of New Jersey, said, “It would be awkward. It would be very awkward.”

Nowhere is the consternation greater than among the hundreds of top donors and “bundlers” who cut their teeth on Bush family political campaigns. If Bush runs, they must choose between bucking their ties to the “first family” of Republican politics or turning their back on Christie, who does not take well to disloyalty.

“Those of us that have been dedicated to the Bush family for years would obviously have to take a Jeb candidacy into extremely serious consideration,” said Fred S. Zeidman, a Texas businessman and top fundraiser for George W. Bush’s two presidential campaigns who helped connect Christie to potential backers in his state.

Christie and Bush have not officially declared their intentions for 2016. Christie’s advisers say his political focus this year remains on leading the Republican Governors Association, which has broken fundraising records during Christie’s tenure as chairman, which began in November.

The presidential chatter is “irrelevant to us,” said William J. Palatucci, Christie’s top adviser and a former law partner. “You know it’s out there, but it’s just not part of our conversation.”

Bush’s flirtation with a White House bid, however, has interrupted Christie’s carefully honed plan to rebuild the faith of donors shaken by a series of high-profile scandals and resignations within his administration.

Until Bush emerged as a potential 2016 contender, these donors said, they had no real alternative but to hope for Christie’s rehabilitation.

“They feel good about Jeb,” said Barry Wynn, a fundraiser for George W. Bush and a former chairman of the Republican Party in South Carolina. “They don’t have any questions about his integrity.”

The family name, he said, remains a powerful draw. “They love the Bush family,” Wynn said. “They love the whole package, and they feel Jeb is just a part of the package.”

In interviews, a number of the donors and fundraisers acknowledged that the interest in Bush was a measure of the creeping doubts about Christie’s ability to either fully rebound from his troubles or to win over conservative skeptics to secure the Republican nomination.

“I don’t know that Chris will be there at the end of the day,” said Whitman, who has previously endorsed Christie and has donated to his campaign.

Gauging the softening of Christie’s support among GOP donors is difficult: He is now raising money almost exclusively for GOP governors who are up for re-election, not for himself. Still, some donors acknowledged that the qualities that made Christie seem special were equally present in Bush, who thrived in a politically diverse swing state and has forcefully challenged GOP orthodoxy on immigration and education.

At risk for Christie is not just the electoral affections of Bush loyalists, but also the backing of a still-potent national network of GOP donors and bundlers who propelled three Bushes to high office and who provided Mitt Romney with an overwhelming fundraising advantage in 2012.

While many have retired from active politics, those who remain constitute a hyperloyal and energetic band of brothers (and sisters). Many of them served as “Rangers” and “Pioneers” within the vaunted hierarchy of Bush fundraising, and went on to plum appointments and ambassadorships in George W. Bush’s two administrations.

Even a decade later, former Rangers and Pioneers heavily populate the ranks of the party’s elite bundlers, a group that the party’s 2016 aspirants began courting almost before President Obama was inaugurated for his second term. Several said they would continue to evaluate the field – unless, that is, Bush steps in.

“I have great affection for Christie,” said Mel Sembler, a Florida real estate developer and Bush donor who is among the top GOP fundraisers. “He’s done an amazing job as a Republican governor in a Democratic state. But I have great loyalty to that family because they brought me into the political arena, and I’ll be supporting Jeb Bush if he decides to run.”

Meanwhile, George W. Bush said Thursday on CNN, “I hope Jeb runs. I think he would be a great president. I have no clue what’s on his mind, and we will talk when he’s ready.”