Updated Feb. 28, 2017 9:09 a.m. ET
HONG KONG—Michael Tien, one of nearly 1,200 electors who will select Hong Kong’s equivalent of governor in March, said he received an unusual request recently.
A caller claiming to represent the interests of Beijing asked Mr. Tien to ditch the candidate he supported and back another: Hong Kong’s former No. 2 official, Carrie Lam. Mr. Tien, a dapper Hong Kong city councilman and businessman, said he worried that refusing could lead to retribution by authorities in mainland China.
The acquaintance who called him “was a person deeply connected in China, whom I cannot name for obvious reasons,” said the 66-year-old Mr. Tien. “I was surprised by the boldness of the call, since I have been so public about supporting another candidate.” Mr. Tien said he was unpersuaded.
Other electors and candidates in the race have also acknowledged the existence of calls or pressure from Chinese individuals claiming government backing and urging them to support Ms. Lam. The electors have until March 1 to publicly nominate a list of finalists who will contend in a March 26 ballot.
On paper, Hong Kong, a former British colony, is a semiautonomous region of China with substantial leeway to elect its leaders. In practice, China’s thumb is on the scales, encroachment that has some here worried that other hallmarks of autonomy could be eroded as well.
While political analysts say China has influenced elections in the past, including indicating preferences for candidates, the influence has deepened recently, with pressure to pick certain candidates more widespread and beginning earlier in the process.
“What’s going on now is even more outrageous than what happened in the past,” said Willy Lam, a professor at the Chinese University of Hong Kong. “The election is becoming more of a typical Chinese election, where the winner is known before the ballots are even cast.”
The China Liaison Office, the central government’s headquarters in Hong Kong, denied allegations that Beijing is working behind the scenes to influence the vote.
Chinese authorities already approve the candidates, who are nominated and then selected by an electoral committee stacked with pro-Beijing members.
Across China, Chinese President Xi Jinping is tightening political control ahead of a Communist Party congress later this year that is expected to further cement his leadership. For Hong Kong, that means having a leader in place who can avoid disturbances like the pro-democracy protests that paralyzed the city in 2014, China experts say.
Until January, Mr. Tien’s candidate, Regina Ip, was thought by many in Hong Kong to be Beijing’s favorite. Though unpopular in Hong Kong, the 66-year-old former security secretary burnished her pro-China credentials trying to pass an authoritarian anti-sedition law in 2003. The move brought a half million protesters to the streets, and the law fizzled.
In January, Mr. Tien and others said the phone calls began, urging them to get behind Ms. Lam, who had recently entered the race. Ms. Lam, who had been the second-highest ranking Hong Kong official after current Chief Executive C.Y. Leung, showed her loyalty to Beijing by leading a government response to the 2014 pro-democracy protests.
Beijing approved Ms. Lam’s candidacy in days while others waited weeks, creating a buzz around Ms. Lam’s bid.
Ms. Ip told local media she was getting phone calls with offers of government jobs if she dropped out of the race, offers she said she refused. She declined to comment.
The Lam campaign rejects the notion that the race is already decided. Though not acknowledging direct support, campaign official Bernard Chan says encouragement from Beijing is only one element in the race. Mr. Chan is organizing Lam campaign rallies to build her popularity, which he says can influence the decisions of the electors.
“If this is a done deal, then why am I working so hard?” he asked.
One reason: Beijing could change its mind. In the last election, Chinese authorities appeared to support one candidate, only to push for Mr. Leung late in the race, according to political analysts. This time, Mr. Leung had been expected to run for a second term but bowed out—under pressure from Beijing, analysts say. Mr. Leung has denied Beijing influence and said his decision was personal.
The underdog candidate is John Tsang, a popular, mustachioed former finance secretary who went to high school and university in the U.S. Hong Kongers applaud him for openly supporting the city in a recent soccer match against a Beijing team, as other politicians declined to commit.
Polls show Mr. Tsang is more popular than Ms. Lam. The same polls show locals expect Ms. Lam to win because she has Beijing’s support.
But Mr. Tsang is no stranger in Beijing, either, having worked with Chinese authorities as a Hong Kong official for years. He recently suggested he would consider the controversial anti-sedition law sought by Beijing, a pro-China gesture. Observers have made much of the fact that Mr. Xi singled out Mr. Tsang for a handshake during a 2015 political meeting.
At a crowded Tsang campaign rally recently, supporter Gordon Poon pushed into the news mob and declared: “I support John Tsang because he is the only candidate not totally controlled by China.”
“How can you be sure he is not?” a nearby reporter asked, turning her camera to him.
—Chester Yung contributed to this article.
Write to John Lyons at email@example.com