HONG KONG — The selection in March of the Beijing loyalist Carrie Lam as Hong Kong’s next leader is the latest sign that China will continue to tighten its grip on this city. Political divisions will deepen and mistrust of the government will rise.

Ms. Lam, who was picked to be chief executive by an election committee stacked in Beijing’s favor, has long taken a hard-line approach to suppressing dissent. As the former No. 2 official under the unpopular outgoing leader, Leung Chun-ying, she presided over the political reform process that ignited the Umbrella Movement of 2014, in which tens of thousands of Hong Kongers occupied major thoroughfares for three months demanding democratic rights.

With Hong Kong’s autonomy plummeting to a 20-year low, it’s more important than ever for Washington to affirm its commitment to freedom in Hong Kong. The Hong Kong Human Rights and Democracy Act, introduced by a bipartisan group of senators in February, would put the Hong Kong people’s rights at the center of United States policy toward the semiautonomous Chinese territory.

The legislation, an update to a 1992 law governing relations between the United States and Hong Kong, would authorize the president to freeze United States-based assets of individuals who have suppressed freedoms in Hong Kong and deny them entry to America, require the secretary of state to issue an annual report on Hong Kong’s political situation until at least 2023 and guarantee that Hong Kongers who have participated in nonviolent assembly would not be denied American visas on the basis of their arrest.