The “super PAC” supporting Mr. Bush is set to go on air with television ads this month in the hopes of turning around his numbers. Mike Murphy, his longtime adviser who leads the group, has publicly sounded unconcerned about Mr. Trump’s ascension and insists there is no need to act any sooner.

At the same time, the campaign has had to trim its sails in terms of spending, budget cuts that aides described as prudent rather than desperate. Three junior fund-raising consultants parted ways with Team Bush in recent days; while they were described in some reports as “key,” their roles with the super PAC have ended as well. In many respects, this is the product of Mr. Bush running his pre-campaign and his super PAC in tandem for six months. When the two were disentangled, the campaign was flying without a net, and officials there took some time to adjust.

His fund-raising team, by all accounts, has been among the more tumultuous campaign divisions, in part because of scheduling issues and in part because of personality clashes.