Republican presidential candidate and Florida Sen. Marco Rubio nabbed the endorsement Monday of former GOP presidential nominee Bob Dole. The retired senator from Kansas told ABC News exclusively that he was backing Rubio only because former Florida Gov. Jeb Bush recently dropped out of the race.

"[Rubio] worked for my ’96 campaign in Dade County, Florida, and so I’ve had an acquaintance with him way back in ’96 when he was a hard worker," Dole told ABC News. "As much as I love John Kasich, you know, Rubio is probably a better candidate. And he’s young."

Dole went on to say that he thought Rubio wanted to "grow the party." He then took aim at Texas Sen. Ted Cruz, adding that,"I don’t know what he wants to grow."

Rubio scored second place over Cruz this past Saturday in the South Carolina primary, though Cruz was polling about 3 percentage points ahead nationally. Both were trailing behind mogul and South Carolina winner Donald Trump — another candidate Dole commented on Monday.

"Trump has to start acting like a presidential candidate and tone down the rhetoric and don't insult anybody," Dole said. But he later added that he'd be happy to advise the billionaire, calling the candidate a "pretty smart guy" who "might surprise a lot of people."

Dole was the vice presidential candidate on the Republican ticket in 1976 with President Gerald Ford. The duo lost to Jimmy Carter. Dole failed to get the GOP's nomination twice in the 1980s but landed it in 1996. He got about 41 percent of the popular vote and ultimately lost to Bill Clinton.

He previously told the National Review he was concerned about the campaign of Bush, who suspended his White House bid Saturday night after coming in fourth in the Palmetto State. Dole also said he doubted Trump could unite the GOP like other candidates would.

"We have to have a nominee, Republicans, who can bring the party together and reach out to moderates and independents and not just the far right-wing," he added.

In other Monday-afternoon Rubio news, Arkansas Gov. Asa Hutchinson also endorsed the lawmaker. Rubio has a score of 124 in FiveThirtyEight's endorsement primary, which assigns various point values to politicians based on influence. On the Democratic side, former Secretary of State Hillary Clinton has 468 points.