* Strain shows between wings of opposition coalition
* Contrast with Chavez allies' public show of unity
* Socialist leader still absent and sick, vote may loom
By Diego Ore
CARACAS, Feb 1 (Reuters) - Venezuela's multiple opposition parties took a decade to unite against President Hugo Chavez, but old strains are emerging again just as he could be forced from power by cancer.
The increasingly public tensions between moderates and radicals within the five-year-old Democratic Unity coalition play into the government's hands should Chavez fail to recover from the disease and a new presidential election be held.
"They're beating each other up. They have no respect for agreements, that's the opposition we have," gloated Congress head Diosdado Cabello, the third most powerful government figure after Chavez and Vice President Nicolas Maduro.
After years of in-fighting, election defeats and chaotic attempts to remove Chavez through street protests, an oil industry strike and even a brief coup, some 30 ideologically diverse political groups formed the opposition coalition in 2008.
It had an auspicious start, winning half the total vote in 2009 parliamentary elections. Then it stayed united - and kept egos in check - during a long primary race to elect state governor Henrique Capriles as its 2012 presidential candidate.
Even though Capriles' defeat by Chavez was crushing for many in the opposition ranks, he galvanized them like never before and they had their best showing - 44 percent or 6.6 million votes - at a presidential election during the Chavez years.
Yet troubles began almost the next day with murmurings from some wings of the opposition that the center-left Capriles had been too soft in his public discourse while too controlling in his exclusion of older parties from his campaign.
A thrashing by Chavez's ruling Socialist Party at regional elections held in December, where the coalition took just three of 23 governorships, accentuated the malaise.
HANDLING CHAVEZ'S ABSENCE
Now with Chavez unseen since his Dec. 11 cancer surgery, and a new presidential election soon a real possibility, the differences appear to be widening.
On one hand, Capriles and another state governor, Henri Falcon, have been urging opponents to stay cool and avoid street protests despite concern over the legitimacy of Maduro's now de facto leadership of government.
They both shook hands with Maduro at a recent meeting.
And though they disagree with the ruling, they have insisted Venezuelans must respect a Supreme Court judgment that Chavez's failure to be sworn in for a new term on Jan. 10 did not mean an end to his 14-year rule.
At the other end of the coalition's spectrum of politicians, right-wing legislator Maria Corina Machado led a walkout of parliament when Maduro gave an annual speech that is normally given by the president, and she has been on the streets whipping up student demonstrators.
Other well-known opposition leaders, such as Leopoldo Lopez and Antonio Ledezma, are also pushing for a stronger line.
Former presidential aspirant Diego Arria - who came second to last in the 2012 opposition primary - accused Capriles' Justice First party of big-footing the coalition.
"The opposition was born fractured because it's a collection of various parties where each one keeps their individuality. There's no way to avoid internal tensions and incoherencies," said political analyst Luis Enrique Alcala.
It is all music to the ears of Maduro and Cabello.
Despite rumors of a long rivalry between the pair - Maduro is a civilian ideologue who rose from being a bus driver to one of Chavez's closest allies; Cabello is a military buddy of the president's with close ties to business - they have been embracing in public and mocking those who predicted squabbling.
That, combined with Chavez's endorsement of Maduro as his preferred successor, has served to keep a lid on jostling within the Socialist Party, or PSUV, during his seven-week absence.
Maduro, who appears to be in a potential election campaign mode, misses no opportunity to bash the opposition during daily speeches, ceremonies and visits around Venezuela that are an imitation of his boss's energetic, on-the-street style.
COULD CAPRILES BEAT MADURO?
In almost every speech, he stresses the words "unity," "loyalty" and "discipline" among Chavez's supporters.
In his latest attack on the opposition, Maduro said PSUV lawmakers would present proof next Tuesday of "immense corruption" involving an unnamed senior figure in Primero Justicia (First Justice), the party which Capriles helped found in 2000.
"Maduro is in campaign and Primero Justicia is the stone in his shoe. That's why they attack us," party leader Julio Borges said later on Twitter.
Though past polls showed Capriles to be far more popular than Maduro and other senior government officials, the picture has almost certainly changed now given the vice president has Chavez's blessing and has taken a high profile in his absence.
The charismatic Chavez, 58, has a fanatical following among Venezuela's poor thanks to his own humble roots, common touch and channeling of oil revenues into social projects. That is bound to rub off onto his chosen heir, although no one will ever be able to replace Chavez in the eyes of his supporters.
The cracks emerging in the opposition coalition are another factor leading most analysts to predict Maduro would likely win, albeit in a potentially tight race, should Chavez be declared unfit to rule and an election called a month later as laid out in the constitution.
Though unlikely to break up altogether, perceptions of disunity within the coalition would inevitably demoralize some supporters and put off potential voters.
The intellectual architect of the Democratic Unity movement, Ramon Guillermo Aveledo, insisted however that Venezuelans should see debate within the coalition as a sign of health.
"This is not an army," he told Reuters at his office in Caracas, where coalition leaders meet every week. "In an alliance like this one, each person chooses his own emphasis."
Despite the wide policy differences inside the coalition, there is little doubt about who will be their candidate if there is a new vote. When Aveledo told a recent rally the coalition would again field a unity candidate if there were an election, many in the crowd roared back: "Capriles for president!"
The 40-year-old governor is currently focusing on tasks in his Miranda state and refusing to speculate on another presidential bid. Perhaps with one eye on any future campaign, however, he often berates Maduro and other officials for failing to deal with Venezuela's grassroots problems, including last weekend's jail riot that killed nearly 60 people.
"Maduro, get to work!" he sniped via Twitter. "Stop trying to hide your incompetence with insults and threats." (Writing by Andrew Cawthorne; Editing by Daniel Wallis, Kieran Murray and Vicki Allen)