In this Tuesday, Oct. 28, 2014 photo, pro-democracy protesters spread a yellow banner with the words reading: "I want genuine universal suffrage" at a rally in the occupied areas outside government headquarters in Hong Kong's Admiralty. (Kin Cheung/AP)

MORE THAN five weeks after they blocked roads into three of Hong Kong’s most prominent districts, pro-democracy protesters haven’t given up or gone away. Hundreds are encamped in neat rows of tents on a highway in the Admiralty district, near government offices, and any move by police to clear the site would likely bring out thousands more. A recent poll showed that the Hong Kong Federation of Students, a leader of the protests, has become the most popular political organization in the city.

Despite their staying power and political success, the students are understandably frustrated. In their sole negotiating meeting two weeks ago, local authorities rejected demands that China’s Communist rulers be petitioned to revise rules for the election of Hong Kong’s chief executive that exclude candidates not approved by Beijing. Consequently, student leaders are discussing whether to travel to the mainland in an attempt to “have a direct dialogue with Beijing officials,” as student leader Alex Chow told reporters last week. Mr. Chow and his fellow students are evidently hoping to impress not just President Xi Jinping but also the leaders he will host next week at an Asia-Pacific summit — including President Obama.

Most likely the pro-democracy students won’t be allowed anywhere near the summit — or Beijing, for that matter. But Mr. Obama, who pledged in September to step up support for pro-democracy movements, even when it “causes friction,” ought to take a cue. Though he can’t oblige Mr. Xi to listen to the students, he can make clear that the United States supports their call for genuinely free elections.

Remarkably, the president and his administration so far have failed to do that. On the contrary: A statement issued by the U.S. Consulate in Hong Kong in September declared that “we do not take sides in the discussion of Hong Kong’s political development, nor do we support any particular individuals or groups involved in it.” A subsequent State Department statement, intended to correct that shameful dodge, was choked with convoluted wording. “The legitimacy of the chief executive would be greatly enhanced,” it timidly ventured, if the election “provides the people of Hong Kong a genuine choice of candidates representative of the voters’ will.”

Mr. Obama and national security adviser Susan Rice were reported in another statement to have raised “developments in Hong Kong” with Chinese Foreign Minister Wang Yi at an Oct. 1 White House meeting. That communication, too, was weak: The “universal suffrage” Mr. Obama was said to have called for is already part of the regime’s controlled election plan.

U.S. officials flinch from raising the topic of Hong Kong democracy because they believe it will bring a furious response from a regime that already claims that the Hong Kong protests were instigated by the United States. But as Mr. Obama put it in September, it is important to speak up even when doing so is uncomfortable — and even when it may not bring immediate results. Mr. Xi may not be moved by Mr. Obama, but the president’s support for the students — spoken clearly and in public — would encourage and inspire pro-democracy advocates all over Asia. Silence will do nothing for U.S.-China relations — only embolden those who favor a crackdown in Hong Kong.