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. Court of Appeals for the District of Columbia Circuit — the most recent examples of what Democrats have long considered unreasonably partisan obstruction by Republicans.

In the long term, the rule change represents a substantial power shift in a chamber that for more than two centuries has prided itself on affording more rights to the minority party than any other legislative body in the world. Now, a president whose party holds the majority in the Senate is virtually assured of having his nominees approved, with far less opportunity for political obstruction.