Rubio said he expects the Hong Kong Human Rights and Democracy Act to easily pass in Congress and be signed into law by the president. The legislation, which has bipartisan support in the Senate and the House of Representatives, has emerged as the primary vehicle through which the U.S. government is hoping to deter China from carrying out a Tiananmen Square–like crackdown against peaceful protesters and pressure it into upholding the city’s special status within China. (So far Senate Majority Leader Mitch McConnell, whose wife’s family has extensive business dealings in China, hasn’t specifically endorsed, even as he’s advocated for legislative measures to preserve Hong Kong’s autonomy. A spokesperson for Rubio, speaking on the condition of anonymity to discuss deliberations in the Senate, said the senator’s office did not view McConnell’s failure to reference the act in a recent op-ed on Hong Kong as a slight.)

Among other things, the bill would require the secretary of state to annually certify to Congress that Hong Kong, which operates its own immigration system, judiciary, and currency, is sufficiently autonomous to maintain the favorable treatment on trade and commerce that it receives from the United States. (Hong Kong, for example, isn’t subject to Trump’s tariffs on the rest of China.) It would also empower the U.S. government to impose sanctions on Chinese or Hong Kong officials deemed to be undermining that autonomy or committing human-rights abuses.

In theory, this would equip the United States with plenty of economic and diplomatic leverage to influence Chinese behavior, but in practice it would be difficult to execute.