Democratic Senators work all-night to lovingly handcraft bill worthy of Republicans to toss into garbage.

ABOVE: Senate Majority leader Harry Reid, delirious from lack of sleep, calls a 3:24 AM press conference to announce aliens are contacting him through the coffee machine.

WASHINGTON (Reuters) - With cots and pillows as well as pleas and warnings, the Democratic-led U.S. Senate debated through the night a plan to end the Iraq war.

Republican leaders, using a procedural hurdle, seemed certain to stop a Democratic proposal backed by a majority of the Senate to withdraw U.S. combat troops by the end of April 2008.

A showdown vote on the plan is expected on Wednesday by weary lawmakers when they wrap up an around-the-clock session. Even if the withdrawal measure were to be passed, it likely would face a veto by Republican President George W. Bush.

But the debate underscored mounting opposition in Congress to a war most voters no longer support, as well as Democrats' frustration over their inability to stop it.

"Republicans will need to choose whether they want to protect the president or protect our troops," Senate Democratic leader Harry Reid of Nevada said.

He said he hoped the all-night session would "focus attention on the obstructionism of the Republicans."

Senate Republican leader Mitch McConnell of Kentucky answered back, "The Democrats, unfortunately, are trying to undermine the efforts of our troops and restrict the ability of our generals to carry out their mission."

In fiery exchanges, Democrats noted that more than 3,600 U.S. soldiers have died in the war, now in its fifth year, and that a change in strategy was needed, while Republicans warned a troop pullout would embolden terrorists and increase the risk of attack on the United States.