Senate Democrats took the dramatic step Thursday of eliminating filibusters for most nominations by presidents, a power play they said was necessary to fix a broken system but one that Republicans said will only rupture it further. Democrats used a rare parliamentary move to change the rules so that federal judicial nominees and executive-office appointments can advance to confirmation votes by a simple majority of senators, rather than the 60-vote supermajority that has been the standard for nearly four decades. The immediate rationale for the move was to allow the confirmation of three picks by President Obama to the U.S....