After a trio of landslide wins in Washington, Alaska and Hawaii on Saturday — the best single day of his campaign — Bernie Sanders narrowed his delegate deficit with Hillary Clinton. But he still has a lot of work to do. Sanders trails Clinton by 228 pledged delegates and will need 988 more — a bit under 57 percent of those available — to finish with the majority.That alone wouldn’t be enough to assure Sanders of the nomination because superdelegates could still swing things Hillary Clinton’s way in a close race, but put aside that not-so-small complication for now. The much bigger problem is that it isn’t easy to see where Sanders gets those 988 delegates.