This post has been updated.

MIAMI – When Mitt Romney visits a guava paste and papaya chunks wholesaler here on Tuesday, he’ll pick up endorsements from a powerful trio of Cuban-American Republicans whose support eluded him four years ago but whose political networks could help him this go around in the critical Florida primary.

Republican presidential candidate and former Massachusetts governor Mitt Romney. (JOHN ADKISSON)

Reps. Ileana Ros-Lehtinen and Mario Diaz-Balart, as well as his brother, former congressman Lincoln Diaz-Balart, are scheduled to endorse Romney’s presidential campaign on Tuesday morning in Miami, according to a Romney campaign official. They are expected to join the former Massachusetts governor when he discusses his economic plan at Conchita Foods, a family-owned local business that was started in Cuba but moved to Florida a few years after Fidel Castro took control in 1959.

Ros-Lehtinen and the Diaz-Balart brothers are joining Romney’s campaign as foreign policy advisers and members of his Latin American Working Group. Romney is trying to solidify his support among the state’s GOP establishment, in particular leaders of South Florida’s Cuban-American community, in advance of the Jan. 31 primary. Romney has already won the endorsement of former senator Mel Martinez, another prominent Cuban-American politician, as well as a slew of current Florida office-holders.

But their blessings come at a potentially uncomfortable time for Romney, who last week attacked his leading rival, former House speaker Newt Gingrich, over his “humane” immigration proposal, which Romney decried as “amnesty.”

Ros-Lehtinen and the Diaz-Balart brothers have been among the few Republican proponents of immigration reform in Washington. In December 2010, the three crossed party lines to vote with House Democrats for the Dream Act, which did not pass the Senate but would have given legal status to some children of illegal immigrants.

In an interview Tuesday morning, Ros-Lehtinen said she did not agree with Romney's immigration stance, but is endorsing him because of his economic plan.

“I’m never gonna find a candidate with whom I agree 100 percent of the time on 100 percent of the issues, but I think the election hinges on the economy – which candidate has the most solid plan to create private sector jobs and get our economy back on track," Ros-Lehtinen said. "I don’t agree with governor Romney’s position on immigration, but I agree with him solidly on the economy, and for me that’s the driving force in this election.”

In the 2008 race, Ros-Lehtinen, the Diaz-Balart brothers and Martinez broke against Romney and instead endorsed Sen. John McCain (Ariz.), who won the Florida primary and racked up a sizeable vote margin in the Miami area, home to a critical voting bloc of Cuban-American Republicans.

This time, Romney hopes that advantage will be his.

“I am proud to be working with Ileana, Mario and Lincoln,” Romney said in a statement that his campaign plans to release Tuesday morning. “They’re conservative leaders who will help me articulate my vision to make America more prosperous at home and respected throughout the world.”

In reporting on the new endorsements Monday night, The Miami Herald wrote that Romney had won “the ultimate Cuban-American endorsement trifecta.” The newspaper quoted a supporter of Texas Gov. Rick Perry’s, Miami-Dade School Board member Carlos Curbelo, as calling the news “a major boost” for Romney because in the Miami area, “their support is crucial.”

But the man considered Florida’s most prized potential endorser remains on the fence. Sen. Marco Rubio, a tea party star and perhaps the nation’s highest-profile Cuban-American politician, has been undecided in the presidential primary contest.

In a statement prepared for release by Romney’s campaign, Ros-Lehtinen, who chairs the House Foreign Relations Committee, said: “Mitt Romney believes that America is an exceptional nation and has a strategy to restore our country’s greatness. The Romney plan for economic growth will create jobs and opportunities for all, especially for South Floridians, who are passionate in their pursuit of the American dream.”

Mario Diaz Balart said in a statement that Romney will “work to secure free markets, economic opportunity and human rights for all people around the world.”

His brother, Lincoln Diaz-Balart, who retired from Congress this year, called Romney “a leader who can rebuild our national defense.” In his statement, he added that “our country faces grave threats throughout the world” and that he believes Romney is “ready to face these challenges.”