Sen. Marco Rubio, R-Fla., may be the son of immigrants from Cuba, but in Miami's Little Havana, Cuban American Republicans back another Floridian in the 2016 White House race.

Within the group, former Gov. Jeb Bush leads the freshman senator by 12-percentage points, according to a Bendixen & Amandi poll, the Miami Herald reported. Forty-three percent of Cuban Americans back the son of former President George H.W. Bush and brother of former President George W. Bush, while only 31 percent support Rubio, the newspaper detailed.

In the senator's camp, the lopsided results should keep alarm bells ringing, pollster Fernand Amandi told Politico. The numbers present a "real serious problem" for Rubio as they suggest he may face broad problems across the Sunshine State in its March 15 GOP primary.

"Jeb is an honorary Cuban, but Marco Rubio would be the first actual Cuban American president. So how is the Cuban community not supporting him en masse?" Amandi asked. "Marco Rubio hasn't made a persuasive case to his own community that he can win. And if he can't make that case here, he can't win Florida if the trend holds."

Across Miami-Dade County, meanwhile, Bush similarly leads Rubio by a significant margin, the Miami Herald detailed. The former is backed by 35 percent of registered GOP voters in the 2.5 million-inhabitant jurisdiction, while only 25 percent of residents are currently behind the latter.

Taking Miami-Dade, the only U.S. country that so far has produced two candidates in the 2016 White House race, is crucial to winning Florida, Politico explained. It is the state's most populous jurisdiction and has more Republicans than any other. The GOP also holds a closed primary here, which means that Democrats and independents cannot vote and potentially skew results.

Bush, who speaks fluent Spanish and whose wife, Columba, is of Mexican origin, has been "a favored local political figure for decades," Politico commented. But Rubio has been thought to rival the former governor's popularity, though some may see him as "too young," former state Sen. Alex Díaz de la Portilla told the publication.