One of the wealthiest and most influential Republican donors is throwing his support behind the presidential campaign of U.S. Senator Marco Rubio of Florida, the New York Times reported on Friday.

Billionaire New York investor Paul Singer sent a letter to dozens of other donors on Friday declaring his support for Rubio in a major blow to the struggling campaign of former Florida Gov. Jeb Bush, the newspaper said. They are among the candidates seeking the 2016 Republican presidential nomination.

Asked by reporters in Iowa about Singer's support, Rubio said: "When people donate to us, they buy into our agenda, and I'm glad that he has and it will help us with resources." Rubio added: "Resources alone are not enough . . . but we're grateful to have his help, obviously."