WASHINGTON — With the U.S. Senate having approved major health care reform legislation Thursday during an extraordinary Christmas Eve vote, Barack Obama moved one step closer to reshaping American medicine and accomplishing that which has eluded previous Democratic presidents. But looming as Obama’s final obstacle to signing a bill into law are negotiations to reconcile the $871 billion Senate legislation with a $1.2 trillion health care package passed by the House of Representatives back in mid November. Whether through a formal conference committee of several Senatorsand Congressmen, or driven from the top down by Senate Majority Leader Harry Reid (Nev.)...