WASHINGTON — President Bush and Congress are headed toward another showdown on war spending, this time sparring over nearly $190 billion the Pentagon says is needed to keep combat in Iraq afloat for another year.

Senator Byrd, chairman of the Appropriations Committee, vowed yesterday not to “rubber stamp” the request and said it was time to put Mr. Bush’s policies in check.

“We cannot create a democracy at the point of a gun,” said Mr. Byrd, a Democrat of West Virginia, whose speech during a Senate hearing on the spending request was interrupted several times by cheers of anti-war protesters.

“Sending more guns does not change that reality,” Mr. Byrd said.

The tough rhetoric was reminiscent of last spring, when Congress passed and Mr. Bush vetoed a bill funding the war through September but ordering troop withdrawals to begin by October 1. Democrats still lack the two-thirds majority needed to override a presidential veto. If approved, Congress would have appropriated more than $760 billion for the two wars, having already approved of $450 billion for Iraq and $127 billion for Afghanistan.

Testifying before Byrd’s panel, Defense Secretary Gates acknowledged that America’s “difficult choices” on the war “will continue to be a source of friction within the Congress, between the Congress and the president, and in the wider public debate.”

But Mr. Gates said he hoped Congress would approve money that is needed by the troops.

“Under some of the most trying conditions, they have done far more than what was asked of them, and far more than what was expected,” he said.

Mr. Gates asked Congress to add $42 billion to the $147 billion already requested for the military. The money would pay for the wars in Iraq and Afghanistan in the 2008 budget year, which begins Monday.

Mr. Gates said the extra money was necessary to buy vehicles that can protect troops against roadside bombs, refurbish equipment worn down by combat, and consolidate U.S. bases in Iraq.

Meanwhile, Mr. Gates also acknowledged to Congress yesterday that the Pentagon may have a problem with security contractors.

“My concern is whether there has been sufficient accountability and oversight,” Mr. Gates told the Senate Appropriations Committee, adding that he has dispatched a small team of officials from the Pentagon to Baghdad to gather more facts.

It’s not that the Pentagon lacks the authority to control its contractors, Mr. Gates said, nor that private hires have misbehaved in large numbers. What may be lacking, Mr. Gates said, is sufficient resources and information for the American commanders in Iraq whose responsibility it is to oversee the contractors.

He also was frank about the reason the Pentagon relies so heavily on contractors — 137,000 of all kinds in Iraq.

Meanwhile in Iraq, a wave of bombings and shootings killed at least 50 people and raised fears that Al Qaeda had launched a promised new offensive. The American military acknowledged that violence was on the upswing and blamed it on the terror movement.

In related news, the House yesterday overwhelmingly voted to condemn the liberal advocacy group MoveOn.org for a recent advertisement attacking the top American general in Iraq.

By a 341–79 vote, the House passed a resolution praising the patriotism General David Petraeus, the commander of American forces in Iraq, and condemning a MoveOn.org ad that referred to General Petraeus as “General Betray Us.”

The liberal group’s full-page ad appeared earlier this month in the New York Times and has served as a rallying point for Republicans. President Bush called the ad “disgusting” and criticized Democrats such as Senator Clinton, the front-runner for the party’s nomination, for being afraid of irritating the group.