Republican presidential candidate, Sen. Marco Rubio, R- Fla., addresses the Sunshine Summit in Orlando, Fla., Friday Nov. 13, 2015. (AP Photo/John Raoux)

Frank VanderSloot, a top Republican donor and chief executive of an Idaho nutritional-supplement company, on Wednesday pledged his support to Marco Rubio's campaign for president, giving the Florida senator another top financier in a quickly growing donor network.

"We started out by saying we needed to answer these two questions: Who would be the best president? And number two, who can get elected?" VanderSloot explained to The Washington Post. In the end, he said, "It ended up being the same person."

VanderSloot says he plans to host fundraisers and bundle contributions for Rubio's campaign, as well as give to a super PAC supporting him. He didn't say how large a total investment he planned to make.

The Idaho Republican said he has given to other Republican presidential hopefuls this election cycle, including Scott Walker and Carly Fiorina. He said Fiorina was his second choice.

Jeb Bush, another candidate VanderSloot considered backing, "was losing steam, and the air's out of his balloon," he said.

Rubio is currently on a West Coast fundraising swing. Last month he landed the backing of billionaire donor Paul Singer.