CARACAS (Reuters) – Venezuela’s opposition supporters will take to the streets nationwide on Tuesday to keep up the heat on embattled President Nicolas Maduro and to call on him to let humanitarian aid into the country where food and medicine shortages are rife. Venezuelan opposition leader Juan Guaido, who many nations have recognized as the country’s rightful interim ruler, is seen with students in Caracas, Venezuela February 11, 2019. REUTERS/Andres Martinez CasaresThe rallies will take place nearly three weeks to the day that opposition chief Juan Guaido invoked a constitutional provision to declare himself Venezuela’s legitimate president, arguing that Maduro’s re-election last year was a sham. Most Western counties including the United States have recognized Guaido as Venezuela’s president, but Maduro retains the backing of powerful nations like Russia and China as well as control of state institutions including the military. The two sides are now at loggerheads over the issue of humanitarian aid, which the opposition says has become necessary due to Maduro’s mishandling of the once-buoyant OPEC nation’s economy. The 35-year-old Guaido is coordinating Western relief efforts. Maduro, who denies there is a crisis, denounces the aid as a U.S.-orchestrated show and is blocking the entry of supplies. “We will return to the streets … to demand the entry of humanitarian aid that will save the lives of more than 300,000 Venezuelans that today are at risk of dying,” Guaido told his 1.25 million Twitter followers late on Monday. “This is a time to unite and fight!” Guaido has vowed that the opposition, which he has re-galvanized, will keep protesting in order to keep up pressure on Maduro to step down so new presidential elections can be held. Maduro’s critics had staged two previous major rounds of protests against what they call his dictatorship, the last in 2017, which subsided in the wake of a government crackdown. The current wave kicked off on Jan. 23, with a massive protest in Caracas during which Guaido was sworn in as president in front of thousands of supporters. The ruling Socialists, who have been in power for two decades, said they would also hold a rally in Caracas on Tuesday, to “demand respect of the fatherland’s sovereignty.” Guaido announced on Monday the first delivery of humanitarian aid – vitamin and nutritional supplements for children and pregnant women – to a network of health centers, without explaining how it had made its way into the country. Guaido said it was a small-scale donation given that the government has so far blocked deliveries from an aid collection point in the Colombian border town of Cucuta. Guaido has appealed to the military to disobey orders and let aid in, after previously promising them amnesty. That would spell the beginning of the end for Maduro, analysts say, though there is no sign to date of it happening. Maduro’s adversaries say he has run roughshod over democratic institutions and ravaged the nation’s economy through nationalizations and a corruption-riddled exchange control system. Reporting by Sarah Marsh; Editing by Leslie AdlerOur Standards:The Thomson Reuters Trust Principles.