WASHINGTON — The health care bill Republicans recently pushed through the House would leave 23 million more Americans without insurance and confront others who have costly medical conditions with coverage that could prove unaffordable, Congress' official budget analysts said Wednesday. Premiums on average would fall compared with President Barack Obama's health care overhaul — a chief goal of many Republicans — but that would be partly because policies would typically provide fewer benefits, said the report by the nonpartisan Congressional Budget Office. In some regions, people with pre-existing medical conditions and others who were seriously ill "would ultimately be unable to purchase" robust coverage at premiums comparable to today's prices, "if they could purchase at all," the report said.