Washington (CNN)Florida Sen. Marco Rubio on Tuesday declined to pledge to play nice with a competing presidential candidate he acknowledged as his "mentor", former Florida Gov. Jeb Bush.
Rivalry brews? Jeb and Marco talk friendship
Appearing on CNN's The Lead, host Jake Tapper asked the newly declared GOP presidential candidate whether that meant he wouldn't perform opposition research on Bush, attack him in advertisements or treat him any differently than the rest of the Republican field.
Rubio only promised a "robust competition."
"Nothing that's gonna happen over these next few months, I believe, will change my feelings toward Gov. Bush as a person or what he's done in the past to serve our country," Rubio said. "I think that I can serve this country at this moment in its history better than anyone else who's running."
Rubio, 43, is positioning himself as the leader of the next generation of Republican leaders ahead of a possible general election against Democratic front-runner Hillary Clinton, 67.
But Bush took a softer approach to the potential rivalry.
"He is my friend, and I care for him a lot," Bush told reporters after an event in Ohio on Tuesday. "I really admire him a lot. I'm not good at playing like I'm something I'm not. I am his friend and he's mine and I'm never going to disparage him."
Rubio expressed confidence on Tuesday that the candidate Republicans ultimately choose to face her will share his belief in an active American military presence across the globe, a position that has sharply separated Kentucky Sen. Rand Paul from most of his Republican competitors, including Rubio.
"I'm pretty confident that at the end of this process, our nominee will be someone like that -- whether because they change positions to adopt that view, or because that's who they really are," Rubio said.