Yeah, if the USA "invites" the two sides to Washington then neither side can refuse to attend. Sure. But the Palestinians will (correctly) point out that this is no different to the failed Madrid talks of 1993, the failed Camp David talks of 2000, the failed Annapolis talks of 2007, and the failed talks in Washington in 2010 that weren't even dignified with a moniker. Why keep flogging the dead horse? Forcing them into a room when they have no common ground to discuss ensures that the talks fail: you must first get them BOTH to commit to an outcome, and then they can sit down and negotiate how to arrive at that outcome.
Yemen's Houthi rebels commit to peace plan in letter to UN chief, BBC reports (Haaretz)