CARACAS (Reuters) - Venezuela s opposition received a European Union prize for human rights on Wednesday and urged the world to keep a close eye on an upcoming presidential election where it aspires to end two decades of socialist rule in the OPEC nation. Foes of President Nicolas Maduro failed to dislodge him during months of street protests this year that turned violent killing more than 125 people, and have been dismayed to see him consolidate his power in recent months. But they hope a presidential vote due in 2018 will galvanize exhausted and despondent supporters, and want foreign pressure for reforms to an election system they say is at the service of Maduro s  dictatorship .  In the next few months, there should be a presidential election and we ask Europe and the free world to pay full attention,  Julio Borges, head of the opposition-led National Assembly, said, receiving the Sakharov Prize.  The regime has kidnapped democracy, and installed hunger and misery,  he added during the ceremony at the EU parliament in Strasbourg. The prize, named after Soviet physicist and dissident Andrei Sakharov, was awarded this year to Venezuela s National Assembly and  all political prisoners , according to the citation. Venezuela s opposition won National Assembly elections in 2015, but the legislature has been sidelined by verdicts from the pro-government Supreme Court and the controversial election this year of a pro-Maduro Constituent Assembly superbody.   Another opposition leader Antonio Ledezma, who recently escaped house arrest in Venezuela and fled to Spain, said the EU prize ceremony was a painful moment because of the scores of opposition activists still jailed.  I cannot be happy receiving this prize knowing that in the dungeons of Venezuela there remain, unjustly deprived of liberty, more than 300 political prisoners,  he said.  Maduro, the 55-year-old successor to Hugo Chavez who has ruled Venezuela since 2013, denies the existence of political prisoners, saying all activists in detention are there for legitimate charges such as coup-plotting and violence. Favorite to be the Socialist Party s candidate for the presidential vote, Maduro says he has faced down a U.S.-backed coup attempt by opponents this year. He frequently mocks both Borges and Ledezma in public speeches. The opposition has a dilemma in choosing its candidate for the 2018 race, given that its most popular figures cannot run: Leopoldo Lopez is under house arrest, while Henrique Capriles is prohibited from holding office.   The European Union last month imposed an arms embargo on Venezuela, adding it to a list that includes North Korea and Syria.      