AlHijjah 20, 1436, October 04, 2015, SPA -- Venezuela's President Nicolas Maduro complained on Sunday that U.S. leader Barack Obama's government was delaying its consent for Caracas' proposed new ambassador in Washington, Reuters reported. The governments have been without ambassadors since Maduro's predecessor Hugo Chavez expelled the U.S. envoy to Venezuela in 2008, prompting Washington to retaliate in kind. "I have sought diplomatic channels ... I sent an ambassador but they still have not given him consent after a year and a half," said Maduro, referring to Venezuela's business attaché and top diplomat in Washington, Maximilien Sanchez. "What good relations does the Obama government want if they're not capable of giving consent? What are they waiting for"? he added on state TV. Just as during Chavez's 1999-2013 rule, ties between socialist-ruled Venezuela and the United States have wavered under Maduro between professions of goodwill then strong mutual criticisms. A nascent diplomatic rapprochement earlier this year was set back last month over the case of Leopoldo Lopez, an opposition leader sentenced to nearly 14 years in prison on charges of fomenting violence against the Maduro government. Washington had been pressing for Lopez's release. The Obama government has not named a proposed ambassador to Venezuela. U.S. diplomats in Caracas had no immediate comment on Maduro's criticism over the status of Venezuela's request for Sanchez to be approved as ambassador.