WASHINGTON (CNN) -- The Senate on Wednesday is set to debate a resolution that cites "no confidence" in the Bush administration's national security policies or Defense Secretary Donald Rumsfeld's "ability to carry out the job," a Democratic leadership aide said.

The resolution, which was first proposed by Democratic Senator Barbara Boxer of California, will be offered as an amendment to the Defense Department appropriations bill.

For days, Democrats have promoted the resolution as a significant political move against Rumsfeld and the administration's Iraq policies. (Watch as Rumsfeld plays hardball while President Bush stays above the fray -- 2:43)

However, aides on both sides of the aisle said the debate is likely to be brief and the resolution probably will be killed by Republicans on parliamentary grounds before it gets to a vote.

Even if the measure passes, Rumsfeld will not be removed from office, but the move forces Republicans to cast what would amount to a vote of confidence in Rumsfeld -- one of the architects of the increasingly unpopular war in Iraq -- before November's midterm elections, a Democratic strategist said.

The chairman of the Senate Armed Services Committee, Sen. John Warner, R-Virginia, called the Democratic resolution a "blatant assault on the president that I will oppose," while the ranking Democrat on the committee, Sen. Carl Levin of Michigan, had a different take.

"If I thought the policies would change by Rumsfeld leaving, I'd be all in favor of calling for that," Levin said.

"But I'm afraid these polices are not only in stone, but we have an administration that thinks it's doing just great in Iraq. But they're getting deeper and deeper into a hole."

Defense chief said to have Bush's 'full confidence'
Meanwhile, the White House has responded to a letter from Senate Minority Leader Harry Reid of Nevada that called for a "new direction" in the administration's Iraq policy.

Chief of Staff Josh Bolten nixed the plan of a "phased withdrawal" of American troops from Iraq, saying "any premature withdrawal of U.S. forces would have disastrous consequences for America's security."

"This 'new direction' would lead to a crippling defeat for America and a staggering victory for Islamic extremists," Bolten wrote. "That is not a direction this president will follow."

Further, Bolten dismissed Reid's suggestion that Bush replace Rumsfeld.

"Secretary Rumsfeld is an honorable and able public servant," Bolten wrote. "Under his leadership, the United States armed forces and our allies have overthrown two brutal tyrannies and liberated more than 50 million people. Al Qaeda has suffered tremendous blows.

"Secretary Rumsfeld has pursued vigorously the president's vision for a transformed U.S. military. And he has played a lead role in forging and implementing many of the policies you now recommend in Iraq. Secretary Rumsfeld retains the full confidence of the president."

The defense chief has said he has offered his resignation before, and Bush has refused it. The president said in April that he wanted Rumsfeld to stay, declaring, "I'm the decider."

Rumsfeld outraged many Democrats and critics of the war with a speech last week to the American Legion convention in Salt Lake City, Utah.

He accused these critics of turning a blind eye to "a new type of fascism" and "returning to that old mentality of 'blame America first.' " (Full story)

Rumsfeld then sent a letter to Democrats on Friday, saying he was "concerned" by their reaction to his speech, according to The Associated Press.

"Thought and careful preparation went into what I said," Rumsfeld wrote, according to the AP. "It is absolutely essential for us to look at lessons of history in this critical moment in the war on terror."

Oh how sweet is this? Throw the bum out on his ass. Then maybe he can make another civilian visit to his old buddy Saddam. God, I wish Grimm was around to comment on this.