China may have the final say on who becomes Hong Kong's next leader, but candidates will still have to pass a tough popularity test at home.

Following news that current Chief Executive CY Leung will not be seeking re-election in March 2017, five contenders have emerged to take on the city's top government post. But before getting Beijing's final tick of approval, they must first gain support among a public fraught by contrasting attitudes towards the mainland and issues of independence. "The central government wants this to be as close to a genuine election as possible. What is quite clear that given CY Leung's announcement, the mainland does not want him to stay, so that means Beijing wants this election to have a more, collaborative approach," Linda Li, professor of political science at the City University of Hong Kong, told CNBC on Tuesday.

Pro-democracy protesters react during a rally in Hong Kong on December 11, 2016, against a crackdown on pro-democracy lawmakers and an electoral system skewed towards Beijing ahead of elections for a new city leader. ANTHONY WALLACE / AFP / Getty Images

CY Leung remains unpopular among many Hong Kongers for his government's hardline stance, a fact that may have cost him Beijing's support. Only one candidate, retired judge Woo Kwok-hing, has made his bid official so far. But others are widely expected to announce their intentions soon, including Chief Secretary Carrie Lam, who previously had insisted she would be retiring next year, former security chief Regina Ip, outgoing Financial Secretary John Tsang and former president of the Legislature Jasper Tsang. As a special administrative region of the mainland, Hong Kong is unable to democratically elect its own leaders, with Beijing ruling out open nominations in 2014. The chief executive must first be elected through an Election Committee and then officially appointed by China's government. Hong Kongers are able to elect members to the committee but just 230,000 people, or six percent of the total electorate, are allowed to cast ballots. Voting began on Sunday, with the pro-democracy camp, called the pan-democrats, securing 325 out of the Committee's available 733 seats—their best performance ever. Pro-establishment members are expected to make up the remainder of the Committee. A total of 600 votes are needed for a candidate to win. China will eventually make clear who its favorite candidate is but first, it will want to wait and see how the candidates test public opinion, explained Tim Summers, senior consulting fellow, Asia Program at Chatham House. Amid a tumultuous year that has seen more citizens grow increasingly resentful towards Beijing, "they want a chief executive who's as popular as possible," Summers added. "Someone who has the trust of Beijing and enough popularity among Hong Kong people, which is tough to reconcile."

