Stephen Crowley/The New York Times Hillary Rodham Clinton visited Capitol Hill in 1994 in an effort to lobby support for a universal health care plan for which she was sharply criticized. WASHINGTON, June 9 — No policy issue has bedeviled Senator Hillary Rodham Clinton more than health care. Ever since the collapse of her proposal for universal coverage in 1994, critics have used the issue as prime evidence in their case that she is, at heart, a big-government liberal with a zeal for social engineering. But now, as Mrs. Clinton heads into her re-election campaign and a possible bid...