2016 presidential candidate Marco Rubio reaffirmed his stance against same-sex marriage during a private fundraiser held in Washington on Wednesday.

Two witnesses who attended the function told CNN that a donor, who identified himself as gay, asked the Florida senator about his position on marriage equality during a question-and-answer session.

In response, the Republican senator said he personally believes marriage should be between a man and a woman, and that states should decide whether or not gays can get married.

Last month, Rubio commented on the upcoming Supreme Court case on gay marriage, arguing that it is "ridiculous and absurd" to believe the constitution protests same-sex couples, reports The Hill.

"It doesn't exist. There is no federal constitutional right to same sex-marriage. There isn't such a right," said the presidential hopeful said during an interview on Christian Broadcasting Network's "The Brody File."

"You would have to really have a ridiculous and absurd reading of the U.S. Constitution to reach the conclusion that people have a right to marry someone of the same sex," he continued.

Rubio added that same-sex advocates don't want to debate the issue with state legislatures because "they can't win that debate."

"The advocates of same-sex marriage refuse to go to the legislatures because they can't win that debate; they don't want to have a debate in society," said the GOP contender. "They want courts to impose it on people, and they are not even satisfied with that. They have now gone further. They want to stigmatize, they want to ostracize anyone who disagrees with them as haters."

Earlier this week, Rubio announced that reality television star Rick Harrison of "Pawn Stars" is slated to host his birthday party fundraiser on May 28.

The Florida senator will celebrate his 44th birthday in Las Vegas at a birthday fundraiser at the home of Harrison, who co-owns the World Famous Gold & Silver Pawn Shop, reports The Hill.

Harrison's wife, Deanna, will also host the bash, along with Lt. Gov. Mark Hutchison, who has been designated as Rubio's Nevada campaign chairman.