Beijing reserves the right not to accept the person chosen by universal suffrage to govern Hong Kong, Chief Executive Leung Chun-ying has warned.
He also said the government had yet to decide on a timetable for political reform - drawing criticism from Democratic Party chairwoman Emily Lau Wai-hing, who accused him of being "hesitant".
Leung said a core issue his government would face when tackling electoral reform was the difference between Hongkongers and Beijing on who should hold the city's top job.
"The possibility exists for Beijing and Hong Kong people not seeing eye-to-eye on the best candidate to lead Hong Kong. This is another issue we need to tackle under 'one country, two systems'," he said.
He noted that Beijing had occasionally declined to accept officials nominated by the city's leader, indicating that "it reserves the same right over the chief executive position".
Leung has promised to launch a consultation on political reform in time for the city to elect its chief executive by universal suffrage in 2017, as Beijing has said is possible.
Political analysts have speculated he will start gathering opinions officially when he delivers his policy address in January.
In an interview with Bloomberg in New York on Tuesday, Leung said that while he wanted to deliver on the "popular wish" for universal suffrage, the government "hasn't decided on the timetable". "We will consult with the people. Ultimately it will be by universal suffrage. It's just a matter of timing," he said.
Former chief secretary Anson Chan Fang On-sang took issue with Leung's comments.
"There is no justification for [Leung] to paint such a negative and alarmist picture to an overseas audience," she said. "It is his job to ensure that the necessary changes to Hong Kong's electoral arrangements are in place … As long as [changes to electoral] arrangements provide for an election that is free and fair, Hong Kong people can be trusted to use their votes wisely."
Lau urged Leung to start the public consultation as soon as possible.
"Even [Leung's top aide] Cheung Chi-kong said the policy address should not be launched without the key ingredient [political reform], so is it true that we won't have that key ingredient in January?" Lau questioned.
During the interview, Leung also said he was "aware of the rising tension Chinese visitors have brought to Hong Kong, as they swamp shops and buy up daily necessities and homes. [We] will continue to ensure residents come first," he said.
On the economy, Leung reiterated that Hong Kong should look into shipping finance and insurance.