BY ALFONSO CHARDY

Raul Martinez, the charismatic but controversial former Hialeah mayor, is returning to politics to challenge one of the most powerful Republicans in the Cuban-American community: U.S. Rep. Lincoln Díaz-Balart.

Martinez's expected announcement Tuesday in front of Hialeah City Hall pits two South Florida political titans -- both admired by large numbers of Cuban Americans.

The campaign will be deeply acrimonious with charges of corruption, and challenges of who's tougher on Fidel Castro's Cuba. Martinez, 58, a Democrat, is the most serious challenger Díaz-Balart, 53, has faced in his 15 years as U.S. congressman.

For Martinez, the campaign will also be a chance to redeem himself -- running a race he has groomed himself for since the late 1980s when his hopes of replacing the legendary Claude Pepper were dashed after federal prosecutors opened a corruption investigation of his dealings with developers.

The probe led to a conviction, appeal and reversal by an appellate court and two subsequent mistrials.

CASE DROPPED

Martinez never spent a day in prison and the case was ultimately dropped. He remained mayor until 2005 when he stepped down ostensibly to devote more time to family and business.

The political bug never stopped eating away at him, though.

''Once you're in politics there's always that little bichito [little bug] inside,'' he told The Miami Herald.

Martinez said he's a Cuban-American Democrat -- a minority in Miami-Dade -- because he's part of the centrist wing of the party. ``I was a Democrat because I believed in housing. . . . I believed in helping the disadvantaged. . . . Yes, you have to have a strong defense. Yes, you have to have a strong immigration policy, all of that. But you gotta be more humanistic.''

Up for grabs in the sprawling district that covers parts of Broward and Miami-Dade are a growing number of independent voters.

The 21st congressional district -- from western Miramar and Pembroke Pines in Broward through Miami Lakes, Hialeah and Doral south to Kendall in Miami-Dade -- is overwhelmingly Hispanic. It has a majority of registered Republicans: 124,744 versus 101,267 Democrats. But those numbers reflect a drop of 4,558 Republicans and a slight gain of 111 Democrats since 2006. The number of unaffiliated voters has grown to 71,208.

Díaz-Balart has told The Miami Herald and El Nuevo Herald that Martinez's return is part of a ploy by Castro sympathizers to lift or weaken the U.S. trade embargo on Cuba. Martinez insists he is not interested in changing the four-decades' old embargo, though he wants to ease the ''immoral'' restrictions the Bush administration set on family travel to Cuba and on remittances.

''He's muddying the waters,'' Martinez said. ``What is he afraid of?''

Polls show that Cuban Americans are split on the 2004 travel limits, which restrict visits of Cuban Americans to once every three years to see a parent, child or spouse on the communist island.

Díaz-Balart, campaigning Monday with Republican presidential candidate John McCain, said voters must keep Martinez's record in mind when casting their ballot.

''I think he's unfit to be trusted with public office and his record shows that. . . . I've always treated the voters with respect,'' Díaz-Balart said. ``His record is not only of corruption but also vulgarity.''

Martinez would be Díaz-Balart's first serious challenge.

''It's an opportunity for Lincoln to show weakness or flex his muscle. The challenge for Raul would be, is he able to get any support outside of Hialeah?'' said political science professor Darío Moreno, director of FIU's Metropolitan Center, a think-tank.

Moreno said his prior polling for the congressman showed Díaz-Balart has an advantage over Martinez and that the former mayor does not ''travel well'' outside Hialeah.

Martinez counters that a private poll shared with him recently showed he could win by a significant margin. Martinez declined to say who conducted the poll. But a close friend, Jorge de Cárdenas, said the poll showed Martinez ''played favorably'' with Hispanic and non-Hispanic voters in the district, and that 15 percent were undecided.

Martinez has never lost an election since first running for the Hialeah council in 1977. Díaz-Balart ran in 1982 as a Democrat for a Florida House seat and lost. He has won every race since being elected to the Florida Legislature in 1986 as a Republican.

By the time Pepper fell ill with cancer at the age of 88 in 1989, Martinez had set his sights on his congressional seat only to see federal authorities disclose he was being investigated. A grand jury indicted Martinez in 1990 on charges of extortion and racketeering. Martinez, who was suspended from office, denied the charges and later claimed the case was politically motivated.

He said he was investigated and indicted to enable Ileana Ros-Lehtinen to win the seat. Martinez noted that the U.S. Attorney in Miami at the time, Dexter Lehtinen, was Ros-Lehtinen's husband.

Neither Lehtinen nor Ros-Lehtinen responded to phone calls for comment.

Martinez has national party support for his bid. Retired U.S. Sen. Bob Graham is backing him, he says. And last fall, Martinez met with top Democratic Party officials in Washington, including Rep. Chris Van Hollen, D-Md., chairman of the Democratic Congressional Campaign Committee, and Rep. Rahm Emanuel, D-Ill., chairman of the Democratic Caucus and architect of the strategy that helped Democrats win control of the House in 2006.

Martinez pointed to his record in Hialeah for almost three decades. He spoke of affordable housing programs, an improved downtown, better streets and other public works.

PUBLIC WORKS FOCUS

Martinez said in Congress, he ``would focus on public works programs, providing more money for water quality and water abundance in our community, housing, health insurance -- to work with both Democrats and Republicans to bring about a health insurance program that everybody would have access to.''

Díaz-Balart cited efforts to tighten the Cuba embargo, restore Social Security benefits and food stamps to legal immigrants, grant residence to Central American immigrants and secure $100 million to construct a new headquarters for U.S. Southern Command.

Martinez said that, if elected, he will not work with Ros-Lehtinen. ``I want to be able to work with the majority of members of Congress that are progressive-minded and I don't see her that way.''

Herald Staff Writer Beth Reinhard contributed to this report.