Senate Democrats and one Republican on Tuesday challenged President Bush's declaration to be the "decision-maker" on issues of war during a hearing on Congress' war powers.
"Congress has the power to stop the war if it wants to," said Sen. Russ Feingold, D-Wis., who was interrupted by applause from observers in the Senate hearing room. "The president has no plan for ending our mission in Iraq."
Senators asked a panel of constitutional scholars if Congress had the power to end the war in Iraq by withholding funding. The experts said Congress did, but it must pass a bill and a presidential veto.
"I would suggest respectfully to the president that he is not the sole decider," said Sen. Arlen Specter, R-Pa., who also challenged Bush's declaration. "The decider is a shared and joint responsibility."
Feingold, who called the hearing, plans to introduce legislation that would force an end to U.S. involvement in the war in Iraq by ending funding and giving Bush six months to remove most U.S. troops.
Feingold said the proposal is not a way to micro-manage the war.
"It makes no sense to argue that once Congress has authorized a war it can't take steps to limit or end that war," Feingold said. "As long as this president goes unchecked by Congress, our troops will remain needlessly at risk and our national security will be compromised."
Democrats want to send a signal to the administration that it cannot ignore Congress, and they threatened to cut off funding to force troops home.
"By finally setting a limit on our involvement in this misguided war in Iraq, and backing up that judgment with the power of the purse, we could re-deploy our troops from that country and begin to focus on the global terrorist networks that do continue to threaten the United States," Feingold said.
Sen. Orrin Hatch, R-Utah, said Congress can choose to cut off funds, but opposing the new mission demoralizes U.S. troops and encourages enemies in Iraq.
"We've authorized whatever force is necessary to fight this war and then some talk about deauthorizing certain uses of that force. The message to our troops is we no longer support them or their mission," Hatch said.
Another Republican, Sen. Lindsey Graham of South Carolina, said he believes it is constitutional for Congress to exercise the power of the purse at the time of war but a non-binding resolution is a "terrible idea" to declare the war a loss when it's not a loss.
"It's not a question of authority, it's a question of wisdom," Graham said. "I hope the Congress is wise enough to not send a signal to our enemy that we can't stand to fight them."
The resolution declares Bush's proposal to send 21,500 additional U.S. troops to Baghdad and Anbar province "not in the national interest." The Senate could take up the resolution next month.
Vice President Dick Cheney challenged Congress to back up its objections to Bush's plan to put 21,500 more troops in Iraq by zeroing out the war budget.
Other proposals pitch stricter demands.
Democratic Sen. Barbara Boxer of California is pushing a bill that would call for troops to come home in 180 days and allow for a minimum number of forces to be left behind to hunt down terrorists and train Iraqi security forces.
"Read the Constitution," Boxer told her colleagues last week. "The Congress has the power to declare war. And on multiple occasions, we used our power to end conflicts."
Congress used its war powers to cut off or put conditions on funding for the Vietnam war and conflicts in Cambodia, Somalia and Bosnia.
Under the Constitution, lawmakers have the ability to declare war and fund military operations, while the president has control of military forces.
But presidents also can veto legislation and Bush likely has enough support in Congress on Iraq to withstand any veto override attempts.
Not since World War II has Congress issued an official declaration of war, despite lengthy wars fought in Vietnam and Korea.
Congress does not have to approve military maneuvers.
FOX News' Major Garrett and The Associated Press contributed to this report.