WASHINGTON -- On his 100th day ruling the House, Speaker John Boehner, R-Ohio, watched a quarter of his troops abandon him.

Boehner's leadership team relied on a large bloc of Democrats on Thursday to muscle through the spending bill that was the product of six weeks of negotiations with the White House and Senate Democrats.

With the fight over funding the federal government for the rest of the fiscal year behind him, Boehner is heading into a much more difficult and consequential showdown on raising the limit on the nation's credit card with a potentially weaker hand.

The federal debt ceiling, currently just under $14.3 trillion, is projected to be breached by mid-May, and the Treasury Department's accounting tricks will last only until early July. Boehner has promised to oppose raising the debt limit unless Democrats agree to budget reforms, setting the stage for another protracted and acrimonious negotiation.

Boehner's leadership team will begin those talks with a problem among many conservatives, as evidenced Thursday afternoon when 59 Republicans, a quarter of the GOP caucus, rejected the 2011 spending bill as too timid.

Some of them opposed the measure because the Congressional Budget Office said on Thursday that the bill probably would cut far less than the advertised $38 billion amount.

Boehner, House Majority Leader Eric Cantor, R-Va., and House Majority Whip Kevin McCarthy, R-Calif., all strenuously backed the deal, but that wasn't enough to stem the conservative uprising.

Recognizing the small rebellion at hand, Boehner sidestepped any chance of taking a victory lap. He said Thursday that it was no cause for celebration, and that his biggest accomplishment so far was changing the nature of the discussions.

"Is it perfect? No," he said during House debate. "I'd be the first to admit it's flawed. But welcome to divided government."

In the end, Boehner's team relied on what might be called a 75-40 coalition -- 75 percent of his Republican rank-and-file, along with 40 percent of Democrats, supported the pact.

An almost identical coalition provided the decisive votes for a stopgap funding resolution this spring, when 54 Republicans rejected that earlier Boehner-led compromise.

Even Boehner's friends have said the March vote weakened him politically as he entered the most difficult negotiations on the spending bill, leading to an effort to reunify the Republicans last week for the final days of the high-stakes talks.