WASHINGTON — Defense Secretary Gates asked Congress today to approve nearly $190 billion for the wars in Iraq and Afghanistan in 2008, increasing initial projections by more than a third.

The spending request guaranteed another showdown between the Bush administration and congressional Democrats, including Senator Byrd, who declared the Appropriations Committee he chairs would not “rubber stamp” the request.

Testifying before the panel, 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 American bases in Iraq.

“I know that Iraq and other difficult choices America faces in the war on terror will continue to be a source of friction within the Congress, between the Congress and the president and in the wider public debate,” Mr. Gates said in prepared testimony.

“Considering this, I would like to close with a word about something I know we can all agree on — the honor, courage, and great sense of duty we have witnessed in our troops,” he added.

A group of anti-war protesters in the hearing room cheered at several points during Mr. Byrd’s speech, including when the West Virginia Democrat asked Mr. Gates whether America was more secure “as a result of this massive, astronomical investment.”

“I believe the answer is crystal clear. We are not!” Mr. Byrd said.

In February, President Bush requested $141.7 billion for the wars; officials said at the time the figure was only a rough estimate and could climb. In July, the Defense Department asked Congress for another $5.3 billion to buy 1,500 Mine Resistant Ambush Protected (MRAP) vehicles.

Mr. Gates said today another $42 billion is needed to cover additional unforeseen requirements. The extra money includes:

— $11 billion to field another 7,000 MRAP vehicles in addition to the 8,000 already planned;

— $9 billion to reconstitute equipment and technology;

— $6 billion for training and equipment of troops;

— $1 billion to improve American facilities in the region and consolidate bases in Iraq; and

— $1 billion to train and equip Iraqi security forces.

The $190 billion would cover war costs for the 2008 budget year, which begins Monday. Congress was on track this week to pass a stopgap spending bill that would keep the war afloat for several more weeks, giving Democrats time to figure out their next step on the war.

Democrats say they plan to use the spending request as leverage to bring troops home, although they lack a veto-proof majority to do so.

Congress should approve the request as quickly as possible “and without excessive and counterproductive restrictions,” Mr. Gates told the Senate. Doing so, he added, helps the Pentagon to better manage its resources and avoid shifting money around, which often requires additional cash.

Today’s request of $42 billion takes into account Mr. Bush’s decision to bring home five Army brigades by next summer, Mr. Gates said.

To date, Congress has appropriated about $450 billion for the war in Iraq, and $127 billion for Afghanistan.