WASHINGTON — A foreclosure rescue plan that has broad bipartisan support stalled in the Senate on Wednesday in a dispute over taxes.

However, leaders said they were optimistic they could pass the measure before Congress breaks for a weeklong July 4 vacation.

Democrats and many Republicans were pushing for quick approval of the bill, which would allow the government to back $300 billion in new, cheaper mortgages for debt-ridden homeowners facing foreclosure.

But negotiations to complete the measure hit a snag over a bid by Sen. John Ensign, R-Nev., to add a $6 billion package of tax breaks for renewable energy producers. The incentives have bipartisan backing, but House Democrats oppose including them without balancing them with tax hikes to prevent an increase in the deficit.