In addition to landing multiple endorsements from several billionaire donors, a new poll shows that Sen. Marco Rubio is the top GOP presidential candidate among wealthy voters.

According to a CNBC Millionaire Survey, 26 percent of Republican voters with at least $1 million in investable assets support the Florida senator, while 16 percent back Ben Carson and 15 percent support GOP front-runner Donald Trump.

"What surprised me was where Trump is among these voters," said George Walper, president of Spectrem Group, which conducted the survey. "They're wealthy but don't see Trump as one of them."

Back in April, former Florida Gov. Jeb Bush took lead as the top GOP pick in the millionaire survey with 37 percent. However, his support has since dropped down to 11 percent, according to the most recent poll.

Rubio also bests Bush among Independent millionaire voters with 11 percent to 6 percent.

However, the general population of American millionaires favor Hillary Clinton. According to the survey, which questioned wealthy Democrats, Republicans and independents, the Democratic front-runner received 34 percent of support, followed by Rubio with 13 percent. Trump and Carson both came in third place with 9 percent.

Earlier this week, billionaire hedge fund manager Ken Griffin announced that he is backing Rubio's 2016 presidential campaign.

"I'm really excited to be supporting Marco Rubio. He will be the next president of the United States," said the founder of the Chicago-based firm Citadel during an interview with CNBC. 

Griffin, who is considered to be the wealthiest person in Illinois with an estimated networth of $7 billion, said he plans to donate "several millions dollars" to Rubio's super-PAC.

Griffin's announcement comes just weeks after the congressman received a major boost to his presidential bid from influential hedge fund billionaire Paul Singer. He is also being backed by billionaire Florida car magnate Norman Braman.