As the House explores ways this week to trim federal spending beyond the $61 billion in cuts that Republicans have already proposed, Speaker John A. Boehner has said all ideas are welcome - from obscure trims involving mustang roundups out West to major reductions such as eliminating funding for the Iraq security forces.

But such a free-for-all can have surprising results, and one of the biggest Wednesday was a victory for President Obama and a defeat for a Boehner-backed initiative.

Many tea-party-backed freshmen broke ranks with their GOP leaders and joined liberal Democrats in voting to cut funding for an alternative engine for a fighter jet. The F-35 Joint Strike Fighter engine project has long been a frequent but elusive target, as well as one that provided jobs in Boehner's home state of Ohio.

In trying to pass a bill that would fund the federal government through September, Boehner has kept a campaign promise to give everyone a voice in the process. But the engine vote showed that no one can quite predict how it will turn out.

That didn't seem to bother some House Republicans, though. Rep. Steve King (Iowa) said the debate has been so intense because Republicans and Democrats have "years of pent-up frustrations" after floor amendments were previously not allowed for such spending bills.

"This constitutional, republican form of government is messy and debate is messy, but I think it's so important that for the first time in how many years now members can actually take their argument to the floor, have a debate, force a recorded vote on their issue," King said.

The discussion about amendments comes as the House finishes its work on the bill that's necessary to keep the government running beyond early March.

House leaders scheduled a final vote on the measure for Thursday afternoon but warned that lengthy debate on amendments could delay that plan.

The Senate is expected to take up the legislation after it returns from its recess at the end of the month, but the measure is considered unlikely to pass that chamber.

The Obama and George W. Bush administrations sought to cancel the alternate-engine program as a symbol of wasteful spending, but their efforts failed in Congress. Last May, despite Obama's opposition, the Democratic-controlled House voted to keep the project alive.

General Electric and Rolls-Royce - which are building the engine, and have spent about $3 billion on it so far and need perhaps several billion dollars more to complete it - had spread the work to many states.

But the contractors' lobbying efforts proved unsuccessful this time. On Wednesday, 110 Republicans joined 123 Democrats in voting to cancel the engine.