Former Florida Gov. Jeb Bush (R). AP Photo/Morry Gash Former Florida Gov. Jeb Bush's (R) massive super PAC is reportedly mulling opening the floodgates to try to take down a top presidential rival, Sen. Marco Rubio (R-Florida).

The New York Times' Maggie Haberman and Michael Barbaro reported Monday night that the super PAC's chief strategist has even "boated of his willingness to spend as much as $20 million" to halt Rubio's rise in the polls.

And the super PAC, Right to Rise, which has raised more than $100 million, has the resources to launch an all-out attack against Rubio, Bush's one-time ally in the Tallahassee statehouse.

"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," Right to Rise strategist Mike Murphy told The Times.

It's not clear if the super PAC will actually declare war on Rubio, which could backfire among conservative donors and activists who either like Rubio or don't want him severely wounded if he becomes the nominee.

Indeed, Bush's attempt to deliver a hard knock to Rubio during the CNBC last month was largely seen as having backfired.

Bush called attention to Rubio's poor Senate-attendance record and said, as a constituent, he wanted Rubio to cast more legislative votes or resign. Rubio responded by condescendingly telling Bush, "Someone has convinced you that attacking me is going to help you."

As Bush has sagged in the polls and Rubio has surged to become a top-tier contender — regularly at No. 3 in primary polls after outsiders Donald Trump and Ben Carson — Bush has cranked up his criticism of Rubio. A leaked campaign document called Rubio the "GOP Obama" and its opposition research questioned Rubio's viability in the general election.

The Times reported that Bush aides and allies are "seething with anger and alarmed over" Rubio's surge, and that some Bush supporters have even taken to calling Rubio "Judas" because Bush supported Rubio's rise over the years in state politics and during his US Senate run in 2010. Rubio was speaker of the Florida House of Representatives when Bush was governor.

According to the report, Rubio's team is nevertheless preparing for the attack by assembling footage of Bush praising his former ally.

Super PACs, which can raise and spend unlimited funds, are legally required to remain separate from the campaigns. However, Bush is closely tied to his PAC and helped it raise gobs of money while he was still technically exploring a potential White House bid.