WASHINGTON — (CNN) A federal judge ruled Thursday against the administration in a challenge to a portion of the Affordable Care Act brought by the House of Representatives.

At issue is the “cost sharing” provision in the law that requires insurance companies offering health plans through the law to reduce out-of-pocket costs for policy holders who qualify.

The government offsets the added costs to insurance companies by reimbursing them.

But lawyers for the House argued that Congress did not properly approve the money for those reimbursements.

U.S. District Judge Rosemary Collyer, who was appointed to the bench by President George W. Bush, sided with the challengers but said that she would stay her ruling pending appeal.

“The court will enter judgment in favor of the House of Representatives and enjoin the use of unappropriated monies to fund reimbursements due to insurers under Section 1402. The court will stay its injunction, however, pending appeal by either or both parties,” she wrote.

The Obama administration is expected to appeal the decision.

Former House Speaker John Boehner, who led the effort on the suit, called the decision “a victory.”

“Today’s Obamacare decision is a victory for the American people, and for House Republicans, who have stood firm for the rule of law,” he tweeted.

“This case is far from over,” said Timothy Jost, a supporter of the law at the Washington and Lee University School of Law.

He said that last fall the judge was wrong to rule that the House had the standing to bring the case in the first place and that he expects the appeals court to reverse on that threshold issue.

“Ultimately, if her opinion holds, and it is unlikely that it would, it would mean that insurers will have to come up with a way of providing the cost sharing reductions, and that would probably mean increased premiums down the road,” he said.