SANTO DOMINGO/CARACAS (Reuters) - Members of Venezuela s leftist government and opposition coalition began a new round of talks in the Dominican Republic on Friday aimed at resolving the OPEC nation s long-running and often bloody political standoff. Various mediation efforts have failed in recent years: foes accuse President Nicolas Maduro of exploiting dialogue to buy time, while he says the opposition prefers violence. Few Venezuelans expect a breakthrough this time, with opponents demoralized at seeing Maduro consolidate power and position himself for possible re-election in 2018. The Democratic Unity coalition - which failed to dislodge Maduro in months of street protests this year that led to about 125 deaths - is pressing primarily for a guarantee of free and fair voting next year.  It also wants a foreign humanitarian aid corridor to alleviate one of the worst economic crises in modern history, as well as freedom for several hundred jailed activists, and respect for the opposition-led congress.   We ve come to seek solutions to Venezuela s problems: food, medicines, free elections, and the need to restore democracy,  lead opposition negotiator Julio Borges said.  It s a difficult path.  The opposition s bargaining power has been weakened by a surprising defeat in October gubernatorial elections. Furthermore, the multi-party group is divided, with more militant sectors opposing the talks.   The dialogue they are planning to start is a parody ... an instrument for the regime to gain time and keep itself in power,  said Antonio Ledezma, an opposition leader who escaped house arrest this month to seek asylum abroad. Maduro has instructed negotiators to focus on opposition to U.S. sanctions against his government. He was strengthened by the October vote and anticipates another win in mayoral elections set for December, which the opposition is mainly boycotting.  President Donald Trump has slapped individual sanctions on a raft of officials for alleged rights abuses, corruption and drugs crimes, as well as economic measures intended to stop the Venezuelan government issuing new debt.  Maduro wants any potential deal with the opposition to include joint pressure on Washington to back off. He has blamed the U.S. measures for Venezuela s economic problems, which in fact began several years ago amid failed statist policies and a plunge in global oil prices.  We came to demand the immediate end of the economic aggressions against Venezuela,  said chief government negotiator and Information Minister Jorge Rodriguez. There is no indication, however, that Trump would be prepared to ease pressure on Maduro, whom he has called  a bad leader who dreams of becoming a dictator.   On the contrary, U.S. officials say Washington could strengthen sanctions unless Maduro enacts democratic changes. The government also wants recognition for Venezuela s Constituent Assembly, an entirely pro-Maduro superbody elected in July despite an opposition boycott and widespread international condemnation.  With an eye to its push to refinance more than $120 billion in foreign debt, Maduro would like the opposition-led congress to agree to approve any negotiations with bondholders, a potential loophole to get round the U.S. sanctions. Foreign ministers from Chile, Mexico, Bolivia, Nicaragua and host Dominican Republic were acting as guarantors at the talks over two days at the Foreign Ministry building in Santo Domingo.  Major near-term breakthroughs remain unlikely given the complexity of issues on the table and the distance between each side s preferences,  said Eurasia group consultancy. 