President Bush remained noncommittal about whether he will sign sweeping campaign finance legislation that passed the House in the wee hours of Thursday morning.

"I think the president has made clear that he would like to sign something that will improve the system. He will have something declarative to say at the end of the process," White House press secretary Ari Fleischer said, adding that the bill still must go to the Senate to reconcile differences in the two versions before it is sent to the president.

The House voted to approve the largest overhaul of campaign spending rules since the Watergate scandals a generation ago after hours of debate carried into the morning.

The bipartisan vote of 240-189 now sends the measure to the Senate.

Supporters there, led by Sens. John McCain, R-Ariz., and Russell Feingold, D-Wis., hoped for swift acquiescence that would send the legislation to President Bush's desk for his signature, although a filibuster loomed as the last-ditch hope of opponents.

House Republican leaders battled to the end against the bill designed to reduce the role of money in politics, arguing it was stacked against their party and unconstitutional as well.

But in an era in which Enron was the new national shorthand for scandal, they were checked at nearly every turn by a bipartisan coalition led by Reps. Christopher Shays, R-Conn., and Martin Meehan, D-Mass.

"People think money taints every decision that is made in this Congress," said Rep. Sherwood Boehlert. The New York lawmaker was one of 39 rank-and-file Republicans to buck their leadership on a 240-191 late-afternoon vote that bestowed preliminary approval on the legislation.

"We should not be afraid to go into a new era, to leave the old beyond," said another Republican, Rep. Zack Wamp of Tennessee, addressing his remarks to the leaders of his own party.

With so many lawmakers directly affected by the legislation, feelings ran high throughout more than 15 hours of debate. Supporters and opponents routinely accused one another of hypocrisy as they bickered their way through a string of votes.

Even so, well after midnight Democratic Leader Dick Gephardt predicted, "I think we're on the threshold of passing this bill."

The president has generally stayed above the fray, even though the White House stepped in during the day to criticize a late change inserted by supporters as "unfair, unwise and unwarranted."

"The president believes that this should be removed," said spokesman Ari Fleischer, addressing a provision that Republicans charged would benefit Democrats.

Meehan and others insisted Republicans had incorrectly interpreted the provision, which related to long-standing rules governing permissible uses of different types of campaign donations. At the same time they drafted clarifying language and agreed to insert it into the bill before final passage. "I want everyone to feel good about what we're doing," said the Massachusetts Democrat.

And despite Fleischer's comments, two senior Republicans who advise the White House said that Bush's political team had determined that the bill would pass, and that the president had decided against a veto.

Still, the developments on and off the House floor underscored the unpredictability of an issue that has long veered between lofty constitutional concerns and bare-knuckled political combat.

"The current campaign finance system is a disaster and it's an embarrassment to American democracy," said Rep. Bernard Sanders, I-Vt., one of a parade of lawmakers who argued that legislation was needed to rein in special interests. Several supporters made mention of the scandal surrounding Enron, the bankrupt energy-trading company.

But critics argued just as passionately the bill was unconstitutional, and a fraud as well. "This bill does not contain real reform. Instead, this bill strips citizens of their political rights and unconstitutionally attempts to regulate political speech," said Rep. Tom DeLay, the House GOP whip.

The House bill would ban unlimited "soft money" donations to the national political parties, typically five- and six-figure donations made by corporations, unions and individuals.

State and local parties would be permitted to raise soft money, but only in amounts of $10,000 or less. None of the funds could be spent on political commercials.

The bill, pushed to the floor over the opposition of Republican leaders, also would ban the use of soft money to buy "issue ads" within 60 days of an election or 30 days of a primary. These ads are typically purchased by interest groups, and while they stop short of expressly advocating the victory or defeat of a candidate, they often are harshly critical.

The measure also would allow candidates for the House to raise their own campaign money in amounts of up to $2,000 per election, an increase from $1,000. Supporters of the bill declared themselves neutral on the change, and it passed, 218-211.

Another provision, added during debate, stripped out a requirement that would have tightened existing law requiring political broadcasting to be sold at a preferential rate. The legislation's backers nominally opposed the amendment — but the National Association of Broadcasters supported it — and Shays and Meehan carefully avoided calling it a "poison pill" that would doom the measure.

By contrast, they worked intensely to defeat numerous other changes proposed by the GOP leadership.

One, backed by the powerful National Rifle Association, would have suspended the restrictions on soft money advertising for "any matter pertaining to the Second Amendment," which guarantees the right to bear arms. It was narrowly defeated, 219-209.

Backers of the bill established their command over the House floor early in the proceedings, brushing aside two Republican-backed alternatives before winning preliminary approval for their own bill.

The tally included 200 Democrats, 39 Republicans and one independent in favor, and 180 Republicans, 10 Democrats and one independent against.

On another point of contention — the focus of Fleischer's comments — Republicans said the bill contained a loophole permitting party committees to use soft money to pay off any debt — a reversal of current law.

"I don't think it needs to be changed," said Sen. Russell Feingold. The Wisconsin Democrat, a leading supporter of the Senate version of the bill, watched from the House floor while the critical test vote occurred on preliminary approval.

Republicans, he said, were relying on "a strained reading of the language."

But Republicans produced a letter signed by two incumbent members of the Federal Election Commission, saying the Democrats were wrong.

The Associated Press contributed to this report.