WASHINGTON — House Democratic leaders on Wednesday banned budget earmarks to private industry, ending a practice that has steered billions of dollars in no-bid contracts to companies and set off corruption scandals.

The ban is the most forceful step yet in a three-year effort in Congress to curb abuses in the use of earmarks, which allow individual lawmakers to award financing for pet projects to groups and businesses, many of them campaign donors.

But House Republicans, in a quick round of political one-upmanship, tried to outmaneuver Democrats by calling for a ban on earmarks across the board, not just to for-profit companies. Republicans, who expect an intra-party vote on the issue Thursday, called earmarks “a symbol of a broken Washington.”

Both parties are seeking to claim the ethical high ground on the issue by racing to rein in a budgeting practice that has become rife with political influence peddling. So far, though, the Senate is not joining in. House Democrats had tried to reach an agreement with their counterparts to ban for-profit earmarks, but the senators balked, Congressional officials said.