Republican presumptive presidential nominee Donald Trump is likely to decide who his vice president will be just days before the conference, according to Newt Gingrich.

Gingrich, who is tipped to be under consideration for the role, told Fox News Sunday Trump was very decisive and would not make his VP decision until the convention in Cleveland, Ohio on 18-21 July.

"He's probably going to start thinking about it about two days before Cleveland," Gingrich said.

"I think Donald Trump does not want to make a decision until the convention. I think that he's a very decisive person."

He also added that he had not heard anything about his rumoured nod for the position.

"Nobody has called me. Nobody has said would you like to be. Nobody has said, 'Would you be willing to be considered?" he said.

"Nobody has said anything."

His comments came as former presidential hopeful and Florida senator Marco Rubio ruled out the possibility of a Trump/Rubio ticket – something that had proved popular among the electorate, who see him as the most popular choice as VP.

"It's too late for that, I'm running for the United States senate from Florida and you can't run for two offices at once," he told Face the Nation.

When asked if he would consider a VP position if he was asked to drop his Florida re-election campaign, Rubio said he was not prepared to consider it.

"That not, for me, a viable option and I said that months ago," he stated. "The differences in policies that me and Donald have had are too big for something like that to work, it would be a distraction, quite frankly, to his campaign."