Tens of thousands of Hong Kongers marched to the city’s US consulate yesterday, calling on Washington to support their fight for freedom and democracy.

The protesters want the US Congress to pass the Hong Kong Human Rights and Democracy Act (pdf), a bipartisan bill that would mandate an annual assessment of whether the city is sufficiently autonomous from mainland China to continue enjoying special US trade and economic benefits.

What the Hong Kong bill entails

Co-sponsored by lawmakers including Republican senator Marco Rubio of Florida and Democratic senator Ben Cardin of Maryland, the Hong Kong bill aims to reaffirm the US commitment to human rights, democracy, and rule of law. It was introduced in both the House of Representatives and the Senate on June 13, a day after violent clashes erupted in the heart of Hong Kong as tens of thousands pro-democracy demonstrators took to the streets.

The bill would put pressure on Hong Kong and Chinese leaders in a number of ways, requiring the US to:

Perform an annual assessment of whether Hong Kong is autonomous enough to justify its continued enjoyment of special status granted under the 1992 Hong Kong Policy Act, which gives the city preferential trade and economic benefits.

Freeze the assets of—and bar US entry to—officials who are found to be complicit in suppressing basic freedoms in Hong Kong, including the rendition of individuals to mainland China.

Perform an annual assessment of whether Hong Kong is adequately enforcing US export regulations, as well as US and UN sanctions.

Waive visa denials for individuals who have been arrested as a result of their participation in the nonviolent protest activities related democracy, human rights, and the rule of law.

Donald Trump has linked Beijing’s willingness to resolve issues raised by the protesters’ demands to any new trade deal with China.

Potential effects on Hong Kong

The biggest impact would likely come from a revocation of Hong Kong’s special status, which differentiates it from the rest of China and hence has shielded it from tariffs on Chinese goods levied as part of the US trade war.

The special status affords other benefits as well, including allowing Hong Kong residents to circumvent visa restrictions that otherwise apply to mainland Chinese citizens, enabling the purchase of sensitive technologies, and ensuring free exchange between the US and Hong Kong dollars. It also lets Hong Kong negotiate trade and investment agreements independent of Beijing.

What US lawmakers have said

Senate minority leader Chuck Schumer, the New York Democrat, has said that addressing China’s actions in Hong Kong will be among the top priorities as Congress returns from its summer recess today. He has urged Senate majority leader Mitch McConnell of Kentucky to put the bill up for a vote. McConnell said last week in a he would support legislation that enhances the Hong Kong Policy Act, which he authored in 1992.

Meanwhile, House speaker Nancy Pelosi, the California Democrat, has said that she looks forward to “swiftly advancing” the bill “in the face of Beijing’s crackdown.”

In an op-ed in the Washington Post last week, Rubio said that the bill would mandate sanctions against Chinese and Hong Kong officials who have committed “serious human-rights abuses.”

What China has said

China has long slammed what it sees as US interference in its domestic affairs in Hong Kong, and this bill is no exception.

Last week, the spokesman for the Chinese Foreign Ministry called on the US to immediately cease work on the bill. “They’ve threatened to push the relevant Hong Kong-related legislation, wantonly criticized Hong Kong affairs, and grossly interfered in China’s internal affairs,” he said. “China deplores and firmly opposes that.”