President Obama could get a second chance to sell Congress on the military operation in Libya, thanks to some last-minute help from an unlikely ally: House Speaker John A. Boehner.

On Thursday, with some liberals and conservatives trying to get Congress to force a withdrawal from Libya, Boehner (R-Ohio) offered an alternative. He introduced a resolution that would give Obama 14 more days to make his case.

Boehner’s resolution would vent congressional anger, stating that “the president has not sought, and Congress has not provided, authorization” for the operation. It also contains a threat that Congress might cut off funding if Obama defies Congress.

But the resolution stops short of demanding that the operation stop and doesn’t declare that Congress officially disapproves of it.

“It does not have Congress taking a stand,” said Rep. Michael R. Turner (R-Ohio), who had attracted more than 60 cosponsors for a separate bill saying that Congress disapproved of the Libya operation. Obama “has already had 75 days. I don’t believe that there’s additional information that he’s going to provide.”

The U.S. military joined the campaign to protect civilians against the forces of Moammar Gaddafi on March 19, and provides a significant amount of the logistical and intelligence support for the NATO-led effort. Under the 1973 War Powers Resolution, Obama was required to obtain congressional approval for the campaign within 60 days of notifying Congress that it had started.

Last month, that deadline came and went.

The Senate reacted slowly: Legislators introduced a resolution supporting the effort, then went on recess. But this week, an unexpected coalition in the House has turned sharply against the effort.

On Wednesday, Republican leaders had to abruptly shelve a proposal from one of Congress’s perennial outliers — Rep. Dennis J. Kucinich (D-Ohio) — that would have demanded Obama withdraw forces from the Libya campaign within 15 days. The bill turned out to have much broader support than expected.

Boehner’s resolution was intended as a less-drastic way to express congressional unhappiness. In a meeting with fellow Republicans on Thursday afternoon, Boehner said of Kucinich’s bill that it would be wrong to abruptly pull out of a NATO-led operation.

“We will have turned our backs against our NATO partners who have stuck by us for the last 10 years,” Boehner said, according to an account from an aide. A spokesman for Defense Secretary Robert M. Gates said something similar Thursday: “To unilaterally abandon [the Libya] mission would have enormous and dangerous long-term consequences.”

On Friday, aides said, the House is expected to vote on both proposals. If Boehner’s resolution passes, some Republicans said they hope Obama takes advantage of the do-over.

At the White House on Thursday, however, press secretary Jay Carney gave no signal that Obama will change the way he has dealt with Congress on Libya.

“We believe that the goal the president has is shared by a vast majority of members of Congress,” Carney said. “And we have consulted with Congress every step of the way since we have initiated this policy.”