WASHINGTON Harsh realities are testing president Barack Obamas :yes we can: ethic like never before as he appeals to Congress and the nation to keep alive his hopes for creating affordable health care for all.  Just hours before Obamas speech to a joint session of Congress on Wednesday night, a leading lawmaker all but abandoned months of effort to bring both parties together in a historic compromise aimed at extending coverage to the nearly 50 million uninsured.  That development quickly followed another dispiriting turn of events for advocates of a radical fix for the health care system. The idea of forming a government-run insurance plan to compete in the marketplace, once at the core of Obamas approach, was close to being written off in Congress, judging by the sentiments of moderate Democrats whose votes are crucial to any reform.  Obamas speech was the opening salvo in an autumn campaign to salvage his top domestic priority. Next up: a rally Saturday in the Midwest.  :We do intend to get something done this year,: Obama said on ABCs :Good Morning America.: