A top U.S. lawmaker has warned President Barack Obama he will violate a law unless U.S. operations in Libya end by this Sunday, or he asks for and receives congressional authorization to continue the mission.

The speaker of the House of Representatives, Republican John Boehner, issued the warning in a letter to Mr. Obama Tuesday.

Boehner asked the president to explain by Friday the legal grounds for the Libya operation.

In response to Boehner's letter, White House spokesman Tommy Vietor said officials are in the final stages of preparing information for Congress on many issues about U.S. efforts in Libya. He said the Obama administration will also provide its legal analysis of the 1973 War Powers Act, the law in question.

The law calls for the president to notify congressional leaders within 48 hours of U.S. military actions. It also prohibits U.S. forces from being involved in military efforts for more than 60 days without congressional authorization, and includes a 30-day withdrawal period.

Mr. Obama in March notified Congress of his decision to take military action in Libya, but did not seek congressional approval.

Also Tuesday, Democratic Senator Carl Levin told reporters a proposed Senate resolution authorizing limited U.S. involvement in Libya could be considered by the Senate Foreign Relations Committee later this week.

Republican Senator John McCain said such a resolution should require the Obama administration to report to Congress all aspects of the Libya mission.

McCain also said the U.S. will not send ground troops into Libya under any circumstances.