Vucic, 47, took the oath of office to succeed outgoing President Tomislav Nikolic at a brief ceremony at parliament, hours after "Against Dictatorship" protests, supported by the majority of opposition parties and leaders, began in front of the building in Belgrade, RFE/RL reported.
Once an ultranationalist who served as information minister in the administration of strongman Slobodan Milosevic, Vucic has solidified his grip on power by reinventing himself as a reformer committed to Serbia's drive toward European Union membership.
His first-round presidential election victory on April 2 came nearly a year after his Serbian Progressive Party (SNS) won parliamentary elections and gives them control over the entire legislative and governing process, which some critics warn could push the Balkan country back into the autocracy Milosevic symbolized during his decade in power.
"Vucic will retain de facto control over Serbian politics," the political risk consultancy Teneo Intelligence said in a May 30 note on the country. "The new prime minister is expected to stay the policy course and keep most of the cabinet members in place."
Read alsoThousands of Serbs continue protests against big election win for PM VucicWith tensions simmering between ethnic Serbs and Albanians in Kosovo, an ethnically charged political stalemate in Macedonia, and accusations of Russian interference in Montenegro's move into the NATO military alliance and toward the EU, concerns have grown over Serbia's direction and how it could reignite the Balkan powder keg.
While Vucic pledges to prepare the nation of 7.3 million people for EU accession by 2019, he also opposes joining NATO. Simultaneously, Vucic has also pushed for deeper economic and diplomatic ties with longtime ally Russia, and he has condemned Western sanctions against Russia for its actions in Ukraine, including the occupation and annexation of Crimea.
This has set off alarm bells in Washington and Brussels over the government's true policy direction, with officials decrying what they call attempts by Moscow to exploit tensions in the Balkans to hinder progress toward integration in structures such as the EU and NATO.
Moscow has also long curried favor in Serbia with its staunch opposition to the 1999 NATO bombing campaign to drive Milosevic's forces from Kosovo. The Kremlin, like Serbia itself, still does not recognize an independent Kosovo.
Serbia has seen dozens of peaceful protests since Vucic's first-round election victory, which demonstrators say came amid major irregularities in the campaign, including stifling the media, voter intimidation, and bribes.
A second rally against Vucic is scheduled for later on May 31 in Belgrade.
