Democrats stepped in to support bringing the aid package to the floor, in a remarkable breach of custom on a key vote that paved the way for its passage.

The House took a critical step on Friday toward approving a long-stalled package of aid to Ukraine, Israel and other American allies, as Democrats supplied the crucial votes to push the legislation past Republican opposition so that it could be considered on the floor.

The 316-94 vote cleared the way for the House to bring up the aid package, teeing up separate votes on Saturday on each of its parts. But passage of those measures, each of which enjoys bipartisan support from different coalitions, was not in doubt, making Friday’s action the key indicator that the legislation will prevail.

The rule for considering the bill — historically a straight party-line vote — passed with more Democratic than Republican support, but it also won a majority of G.O.P. votes, making it clear that despite a pocket of deep resistance from the far right, there is broad bipartisan backing for the $95.3 billion package.

The vote was an enormous victory in the long effort to fund to Ukraine as it battles against Russian aggression, a major priority of President Biden that has met with bitter resistance from the right. It was a triumph against the forces of isolationism within the G.O.P. and a major moment of bipartisan consensus in a Congress that for the past year has been mostly defined by its dysfunction.