Virginia’s House of Delegates has taken the first step toward awarding the state’s electoral votes proportionally, rather than via the current winner-take-all system. The move would make Virginia the third state, along with Maine and Nebraska, to allocate Electoral College votes by giving one to the winner of each congressional district and two to the statewide winner. The change, which was approved by a House subcommittee, still needs to pass the entire House. And even if that happens, it would face strong opposition from Democratic Gov. Terry McAuliffe and the state Senate, where an identical bill failed to make it through committee. But this isn’t the first time Republicans in Virginia and other states have raised the possibility of moving away from winner-take-all allocation. How much of an advantage could Republicans gain in presidential elections by moving states to a system that distributes electoral votes based on the number of congressional districts each candidate wins?

We can check by using Daily Kos Elections’ newly released data that breaks down presidential vote by congressional district. The main takeaway: In an Electoral College in which every state awards its votes by congressional district, Hillary Clinton could have won the national popular vote by 5 percentage points and still lost the White House.