For many of Mr. Bush’s longest-serving advisers, Mr. Rubio’s run is a betrayal: Mr. Bush backed Mr. Rubio’s bid for House speaker in Florida and persuaded important donors to endorse him for the Senate. A few of Mr. Bush’s supporters have taken to calling Mr. Rubio “Judas.”

In meetings with donors and allies, Mr. Bush’s top aides have pointed to what they describe as a trove of research on Mr. Rubio that they could unleash.

Any attacks on Mr. Rubio would come primarily from Right to Rise, the “super PAC” that has raised more than $100 million for Mr. Bush. Its top strategist, Mike Murphy, refused to detail its strategy but did not dispute that Mr. Rubio was in its sights.

“Part of running for president is you have to put your big boy pants on and get vetted on the issues, so we know we don’t have a dud candidate running against Hillary Clinton,” he said.

Asked about the multiple videos of Mr. Bush praising Mr. Rubio over the years, Mr. Murphy said of Mr. Rubio: “We all supported him for the Senate. We all support him staying there, because he is far from proving he is ready and experienced enough to be president of the United States in a dangerous time.”

Mr. Murphy’s critique echoed an internal Bush campaign memo outlining Mr. Rubio’s vulnerabilities. Under the headline “Marco is a risky bet,” the memo, which surfaced on Oct. 29, said Mr. Rubio “has never been in charge of anything larger than two dozen people.”