WASHINGTON, July 23 — The House of Representatives overwhelmingly passed legislation today to block a new rule supported by the Bush administration that would permit the nation's largest television networks to grow bigger by owning more stations.

The vote, which was 400 to 21, sets the stage for a rare confrontation between the Republican-controlled Congress and the White House, because there is strong support in the Senate for similar measures, which seek to roll back last month's decision by the Federal Communications Commission to raise the limit on the number of television stations a network can own. The F.C.C. has ruled that a single company can own television stations reaching 45 percent of the nation's households, but the House measure would return the ownership cap to 35 percent.

Only a few weeks ago, support for the F.C.C.'s move by House Republican leaders had been expected to counter the Senate uprising. But many House members from both parties have evidently taken note of the vocal resistance to the F.C.C. action by many members of the public and a broad spectrum of conservative and liberal lobbying groups — from the National Rifle Association to the National Organization for Women.

Today's House rebuke of the F.C.C. was embedded in a spending bill. The White House, which has threatened to veto the bill if the network provision remains in it, today sought to play down the lopsided size of the vote. Claire Buchan, a White House spokeswoman, said that presidential advisers had recommended approval of the legislation so that it could proceed to a House-Senate conference committee where the network ownership provision might be stripped out.

If, as is becoming more likely, the provision survives in final legislation, President Bush will face a difficult political predicament. He could carry out his veto threat and alienate some of his traditional constituents, which include several conservative organizations opposed to a number of new rules adopted by the F.C.C. Or, he could sign the legislation, abandon the networks and undercut his own advisers who have recommended that he reject the legislation.