After a strong debate performance Wednesday that boosted his profile, invigorated his early state supporters, and marked him as a contender on the rise, the presidential campaign of Marco Rubio has capitalized on his growing momentum by fortifying its fundraising strength.
On Friday, billionaire and Republican donor Paul Singer, a fundraiser coveted by Rubio's rivals, endorsed the U.S. Senator from Florida.
"We're grateful to have his help," Rubio said to reporters while campaigning in Iowa Friday on Singer's endorsement.
"Marco Rubio can appeal to both the head and the heart. He can lead our nation by inspiring it", Singer, who met with Rubio last week, wrote in a letter to his donor network that was first reported by the New York Times.
The announcement by Singer, came on the same day that a major pro-Rubio super PAC, Conservative Solutions PAC, announced that they would be ramping up their efforts, including a new TV ad, to " bring Marco's optimistic conservative to as many voters as possible."
In a memo, obtained by Fox News, the powerful PAC with millions in reserves, informed their donors that they believed Rubio was one of four Republican candidates with a" reasonable chance" of becoming the party's nominee, and the only one who had the "best chance to win" among the GOP field in a general election.
Omitted from the four by Conservative Solutions PAC-- that along with Rubio, included Dr. Ben Carson, billionaire Donald Trump, and Texas Sen. Ted Cruz – was former Florida Gov. Jeb Bush.
Bush and Rubio, who still consider each other friends publicly, clashed during the CNBC debate in Boulder, Colorado.
Though Bush's fundraising operation has raised more than Rubio up until this point-- the pro-Bush super PAC alone has raised over $100 million-- both are vying for many of the same donors. Singer backing Rubio was a blow to Bush, however.