The race to be the presidential candidate of Venezuela's opposition coalition has come down to three challengers who all hope their youth and experience in office make them the best bet to unseat President Hugo Chavez.

Less than a year ahead of the South American OPEC member's October 7 vote, politics are dominated by two issues: the health of socialist leader Chavez after cancer treatment, and who will win the Democratic Unity coalition's February primary.

The three frontrunners in the opposition tussle ahead of a February primary are state governors Henrique Capriles Radonski and Pablo Perez, and former district mayor Leopoldo Lopez.

With ages ranging from 39 to 42, they have successfully presented themselves as the new guard of Venezuela's opposition, pushing out traditional party heavyweights with poor records against Chavez.

The doors are opening to a new way of doing politics, said Lopez, flanked by his wife and cheering supporters as he formally registered for the primary this week.

Lopez, who used to be mayor of Caracas' wealthy Chacao district and is known for his telegenic looks and charismatic oratory, is the most-recognized abroad of the three men because of his legal fight after being disqualified from politics.

After a regional human rights court ruled in his favour earlier this year, Venezuela's Supreme Court decreed that he could run for president -- but that he remained barred from holding office because of a pending graft investigation.

Lopez says Chavez is scared of him and the charges false.

ENERGETIC FRONT-RUNNER

Ahead of Lopez in all polls of the opposition field is Capriles, the governor of Miranda, Venezuela's second most populous state that includes parts of Caracas.

A keen basketball player, the energetic Capriles often rides a motorbike to work and -- in an echo of Chavez's pre-cancer style -- frequents shanty-towns to supervise projects and inquire about locals' problems. During floods, he was widely pictured wading up to his waist to visit victims.

He is still the frontrunner by some distance. He's the guy most likely to unify the opposition, rally the 'NiNis' and beat Chavez, wrote pro-opposition blog Caracas Chronicles, using a local term for undecided or 'neither-nor' voters.

The nomination is his to lose.

The third big opposition contender, among a large clutch of hopefuls, is Perez, governor of the oil-rich western state of Zulia, on the border with Colombia.

Last week he secured the important endorsement of Venezuela's largest opposition party, Democratic Action.

But while he may benefit from its formidable national political machinery, there could be a backlash among some voters given the party's sullied reputation from nepotism.

Beyond their opposition to Chavez and promises to unite behind whoever wins the primary on February 12, the three men have given few specific policy pledges and are trying to avoid political type-casting in Venezuela's polarized environment.

Analysts say Perez and Capriles -- who is an admirer of former Brazilian leader Luiz Inacio Lula da Silva -- are broadly centre-left, while Lopez is centre-right.

To their nemesis, Chavez, however, they are all representatives of the ultra-right, offspring of Venezuelan bourgeoisie who plan to dismantle his socialist policies at the behest of interests in Washington.

Would that there were a candidate of one's own level to have a debate with, but none of them are fit to look in the face, pure mediocrity, Chavez said in one of his near-daily dismissals of the opposition.

Whoever wins in February faces a formidable battle against Chavez. His approval ratings have risen to near-60 percent on a sympathy bounce over his illness and he has accumulated a large election war-chest on the back of high oil revenues.

Chavez has declared himself cured of cancer after an operation to remove a tumor in his pelvic region and four rounds of chemotherapy. Yet doubts persist.

Doctors say it is impossible to have a clean bill of health until at least two years after cancer treatment, and the president said over the weekend he was not in optimum physical condition because of a cold he caught in the rain.

(Additional reporting by Deisy Buitrago and Marianna Parraga; Editing by Vicki Allen)