Renewed bickering among Zimbabwe's opposition only months after a vow to bury their differences looks set to wreck prospects of a united challenge to President Robert Mugabe at elections next year. After they both fell victim to a crackdown by the security services in March, leaders of the two factions of the main opposition Movement for Democratic Change (MDC) promised they would no longer be distracted from their primary task of ending Mugabe's 27-year rule.