The idea that “experience matters” was the theme of an on-stage conversation between the two brothers at a private event for donors to Bush’s campaign. That theme came through most strongly as Jeb Bush’s staff outlined how they plan to go after Florida Sen. Marco Rubio, who the campaign views as Bush’s top competition for the Republican nomination.

“Put it in the campaign slogan, ‘A proven leader,'” George W. Bush told about 175 of Jeb Bush’s most loyal donors on the second day of the two-day event, according to an audio recording of the meeting.

“He knows how to manage an administration,” the former president said. “I happen to believe eventually the American people will say, ‘Who has the experience necessary to be president? Who’s run a state, for example?”

The donor event arrived at a crucial moment for Bush, a once-dominant GOP candidate who is lagging in preference polls to a pair of political novices with no experience in elected office, retired neurosurgeon Ben Carson and billionaire real estate mogul Donald Trump.

With fewer than 100 days until voting begins, Bush’s campaign is betting that a large swath of Republican voters will ultimately seek out a seasoned politician as their choice for the party’s nominee — especially given the GOP’s widespread dissatisfaction with President Barack Obama, who was elected during his first term in the Senate.

“We are pitching our path to victory. We addressed all the key opponents, including Marco, and will contrast Jeb’s leadership skills with theirs,” Jack Oliver, Bush’s campaign finance co-chairman, told The Associated Press. “Our supporters want someone who is willing to fight for victory and that’s what the team presented.”

A hard-hitting strategy presentation at the meeting focused intensely on Rubio and illustrated how Bush and his team plan to show differences between the two Floridians.

It included a slide that read “Marco is a GOP Obama,” according to documents provided by the campaign. In the presentation from Bush’s campaign manager, Danny Diaz described Rubio and Obama as having “strikingly similar profiles,” that include being lawyers, university lecturers and former state legislators with “few legislative accomplishments.”

Diaz also compared Bush and Rubio’s fundraising and available cash, ignoring all of the other candidates in the GOP race.

Bush’s campaign announced last week it was making sharp spending cuts, mainly to employee wages, so he can intensify the organization’s focus on the first two states to vote, Iowa and New Hampshire. The cuts were calculated based on his and Rubio’s available cash, so as to ensure Bush would have enough to make it to the start of voting in February, campaign aides said.

Rubio’s campaign declined to comment on the Bush campaign’s presentation.

Bush has nudged at his in-state rival while campaigning in recent weeks. In Iowa earlier this month, Bush said voters would rethink their support for Rubio, whom he described as “an eloquent guy” who “had nothing in his background that would suggest he could lead.”

There was no pretense of such subtlety at the donor event. Jay Zeidman, a Houston fundraiser for Bush, said of Rubio, “he’s been a great U.S. senator, but we’re not running for Senate.”

Zeidman said the Bush team has looked at data that has convinced them that voters won’t pick someone “who is not capable of being commander in chief,” a reference to Trump and Carson. The same data also suggest to them that Rubio is Bush’s closest competitor.

George W. Bush hit that theme time and again while sharing the stage with his brother. The former president said he tried to “project calm” after the 9/11 terrorist attacks, and noted how his brother led Florida through its response to eight hurricanes during his two terms as governor.

“This is where experience matters. I think it is instructive to have gone through crises if you are a chief officer,” George W. Bush said. “It’s important that you project calm, as Jeb did when those devastating storms hit.”