Donald Trump won Tuesday’s presidential election. But many liberals and progressives have begun clinging to one faint hope that he could still be stopped — through the Electoral College.

Tuesday’s vote was technically not to make Trump president, but only to determine who the 538 electors in various states across the country will be. It is those electors who will cast the votes that legally elect the president on December 19. 

In modern times, the casting of electoral votes has been a purely ceremonial occasion where the results in the states have been rubber-stamped. But one idea spreading on left-leaning social media circles is that electors from states Trump won should be urged to support Clinton instead. A Change.org petition to this effect has more than 500,000 signatures.