House Speaker John Boehner urged President Barack Obama on Tuesday to explain the legal grounds for the continued U.S. military involvement in Libya and set a Friday deadline for the commander in chief's response.
The White House said late Tuesday it was nearing completion of an "extensive" response to congressional inquiries.
Ratcheting up the pressure, the Ohio Republican said in a letter to the White House that the administration clearly will be in violation of the 1973 War Powers Act this weekend. Obama did not seek congressional consent for the operation within 60 days of the March 19 U.S. airstrikes against Moammar Gadhafi's forces.
"Either you have concluded the War Powers Resolution does not apply to the mission in Libya or you have determined the War Powers Resolution is contrary to the Constitution," Boehner wrote. "The House and the American people whom we represent deserve to know the determination you have made."
Boehner complained that the administration has provided briefings for lawmakers but has not sought formal authorization. Seeking an explanation, he asked Obama for answers to constitutional and statutory questions by Friday.
Earlier this month, the House voted to rebuke Obama for failing to pursue congressional approval and accused the president of not providing a "compelling rationale" for the Libyan operation. The House measure also required a report from the administration, due by Friday, on the scope of the Libyan operation, its costs and its impact on the wars in Iraq and Afghanistan.
"The ongoing, deeply divisive debate originated with a lack of genuine consultation prior to commencement of operations and has been further exacerbated by the lack of visibility and leadership from you and your administration," Boehner wrote.
The White House maintains that it has been in compliance with the War Powers Act and has called the resolutions unhelpful and unnecessary.
Initially the White House brushed off the nonbinding House measure, saying it had provided answers at various briefings. But last week it said it will respond to detailed questions on the U.S. mission in Libya within the deadline.
Responding to Boehner's letter Tuesday, White House national security spokesman Tommy Vietor said, "We are in the final stages of preparing extensive information for the House and Senate that will address a whole host of issues about our ongoing efforts in Libya, including those raised in the House resolution as well as our legal analysis with regard to the War Powers Resolution."
Vietor didn't say exactly what form the White House response would take and whether it would be the type of report sought by the House.
NATO commands the Libya operation, but the United States still plays a significant support role that includes aerial refueling of warplanes and intelligence, surveillance and reconnaissance work.
In the Senate, the fate of a resolution signaling support for the operation was in limbo.
Sen. John Kerry, D-Mass., chairman of the Foreign Relations Committee, said plans for the panel to meet Thursday and write a resolution would be delayed to allow lawmakers to review the White House report. He left open the possibility of action on a resolution next week.
"We just want everybody to see the information and see how it impacts their thinking," Kerry said.
Among the backers of the resolution is Sen. John McCain of Arizona, a leading proponent of military action against Gadhafi, the top Republican on the Armed Services Committee and Obama's presidential rival in the 2008 election. McCain warned his GOP colleagues against any steps that would send a positive signal to Gadhafi.
"I caution my friends, both here in the Senate and in the House of Representatives, that we don't want to do anything or pass legislation which would encourage Gadhafi to remain in power," McCain told reporters.
Sens. Jim Webb, D-Va., and Bob Corker, R-Tenn., introduced a separate resolution last week that presses Obama to seek congressional consent for continued U.S. military involvement in Libya and requires the administration to provide a detailed justification for the decision to go to war.
McCain said there are continued signs of deterioration for Gadhafi's hold on power, including high-level defections from his regime.
"I would say to my Republican friends: If this were a Republican president, would you be trying to impose these same conditions?" McCain asked.
On Monday, the House essentially voted to prohibit money for the Libya operation, backing an amendment barring the use of any funds in contravention of the War Powers Act. The vote was 248-163 on a spending bill that still must be reconciled with the Senate.
One of the most vocal critics of Obama, anti-war Rep. Dennis Kucinich, D-Ohio, said he and Rep. Walter Jones, R-N.C., will file a complaint in federal court Wednesday over the Libyan war.
Associated Press writer Alan Fram contributed to this report.