Congress has a positive role to play when a U.S. president is using the nation’s military might abroad in actions that are critical but don’t rise to the constitutional level of a war declaration.

Libya, however, is the latest example of how 435 House members and 100 senators can’t agree on just what that role should be.

In the past two weeks, the House showed the good and the bad of the situation during its debates and votes focused on President Obama’s March 19 decision to use U.S. forces in support of the United Nations’ military actions against Moammar Gaddafi’s regime.

Meanwhile, senators have done little but talk after taking the lead on March 1 by passing a unanimous resolution supporting the idea of U.N. involvement “to protect civilians in Libya from attack, including the possible imposition of a no-fly zone over Libyan territory.”

Seven weeks later, Gaddafi remains and the air war continues. The U.S. military’s role has been reduced from leading the attacks against ground targets to providing support through intelligence, air refueling, surveillance and search-and-rescue capabilities.

Primarily because success has been slower than expected, individual lawmakers, at both ends of the activist/pacifist spectrum, have criticized the president. Those who supported early intervention have complained about the United States’ withdrawal of its ground attack aircraft and helicopters from the battle. In response, the U.S. government agreed to deploy Predator unmanned air vehicles to the Libyan theater, temporarily quieting those critics.

At the other end, those in the House who initially opposed joining in the no-fly zone now want withdrawal of U.S. forces within 15 days. With continued participation, Obama has violated the War Powers Resolution, they argue. A House-Senate concurrent resolution encompassing that approach, introduced by Rep. Dennis J. Kucinich (D-Ohio) with bipartisan support, was defeated Friday in a vote of 148 to 265.

A resolution, with no enforcement attached, did pass the House last week. It showed the good and the bad of Congress. Introduced by House Speaker John A. Boehner (R-Ohio), it was a mix of partisan politics and support for congressional authority. It may have even helped the White House. Without it, Kucinich’s resolution may have had a better chance.

Boehner’s resolution included criticism of Obama for not providing Congress “with a compelling rationale based upon U.S. national security interests.” It directs the secretaries of state and defense and the attorney general to provide within 14 days all documents created after Feb. 15 that relate to consultations with Congress about the Libyan intervention and the War Powers Resolution — a request that inevitably will raise questions of executive privilege.

It also carries a list of 21 items — for which it reports within the same 14 days — that range from “specific commitments made . . . to ongoing NATO activities regarding NATO,” to “justification for not seeking authorization by Congress for the use of military force in Libya,” to “the composition and political agenda” of the interim Libyan liberation council.

Though it passed, 268 to 145, it had its critics. Rep. Jeff Flake (R-Ariz.) said he was “concerned about the puzzling, confusing, mystifying signal that we send by passing a resolution that affirms that the president has not fulfilled his constitutional or statutory obligations, yet offers no remedy, only a mild rebuke, followed by a questionnaire.”

Rep. Norm Dicks (D-Wash.) described it as “an attack on the president, something most of the Republican caucus would vote against if its party was in control of the executive branch.” But, he added, “I am neither prepared to end our involvement unilaterally, as in the Kucinich amendment, nor do I believe Congress should officially declare our involvement in this effort that has not been properly explained by the president.”

What may turn out to be a good precedent, because neither the House nor the Senate has voted to authorize what the United States is doing in Libya, is what the House did on March 26. It passed, by 416 to 5, an amendment to the fiscal 2012 Defense Authorization Bill that would prohibit deploying U.S. ground troops to Libya for any purpose other than to rescue fellow members of the U.S. armed forces.

Originally introduced by Rep. John Conyers Jr. (D-Mich.), also with bipartisan sponsorship, the amendment took up a pledge that Obama made when announcing the Libyan operation that he reiterated in a speech to the nation on March 28: “We would not put ground troops into Libya.”

In explaining his amendment, Conyers said, “My amendment does not oppose the president’s policy; it would simply enact his promise into law.” Conyers then explained his purpose was not to totally tie the president’s hands should the situation change. He said that if at some point U.S. ground troops were needed in Libya, the president “could come to the Congress and request an authorization for force, which if passed by both the House and Senate would overrule this provision.”

During the Vietnam War, a similar amendment was introduced by Sen. J.W. Fulbright (D-Ark.), then chairman of the Senate Foreign Relations Committee. Fulbright’s panel had made public President Richard M. Nixon’s secret bombing in Laos. In return for allowing the bombing to continue, Nixon had said publicly that he would not send American ground troops into Laos or Thailand.

Using that pledge, Fulbright’s amendment became law, and was the first congressional initiative that limited the scope of the Vietnam War. Fulbright said that if necessity arose, Nixon could come to the Congress, explain what had changed and seek authorization for meeting the new situation. Like Conyers, he did not want to permanently tie a president’s hands.

I know because I worked for Fulbright at the time and with him and others wrote the Laos-Thailand amendment.