The Bush administration is turning aside suggestions that it increase the U.S. military role in Afghanistan following the assassination of an Afghan vice president.

Efforts should focus on training the Afghan army rather than joining the international peacekeeping force, White House spokesman Ari Fleischer said Sunday in Maine, where President Bush spent the weekend.

``The president thinks the best way to secure the Afghan country is through the training of the Afghan army,'' Fleischer said. ``There are plenty of international peacekeepers in Kabul,'' the Afghan capital.

A bipartisan chorus of lawmakers said, however, that U.S. officials may need to become more active following the assassination of Afghan vice president Abdul Qadir, killed by gunmen Saturday in Kabul.

``I fear that we may see this government and our efforts unwind here if we don't make the appropriate investment of men and effort and resources,'' said Sen. Chuck Hagel, R-Neb., a member of the Senate Foreign Relations Committee.

``If we lose there, if this goes backward, this will be a huge defeat for us symbolically in that region, in the world, for our word, confidence in Americans all over the world. We cannot allow this to go down,'' Hagel said on NBC's Meet the Press.

Similarly, Sen. Evan Bayh, D-Ind., said on Fox News Sunday that the United States needed to become more involved.

``If all you do is secure the capital and allow instability to fester around the country, I think we're running a real risk that the gains we made during the war could be lost by an insufficient peace,'' Bayh said. ``My own view is, we went to war, we won the war, let's not lose it now.''

About 7,000 U.S. troops are in Afghanistan, including infantry, special operations air and ground troops, military police and intelligence analysts. They are hunting for Al Qaeda fighters and weapons, and are training a fledgling Afghan army.

Turkey commands the 19-nation peacekeeping force of more than 4,500 soldiers, primarily Europeans. They have provided security in Kabul since the Taliban militia was ousted by U.S.-allied Northern Alliance forces late last year.

Senate Intelligence Committee chairman Bob Graham, D-Fla., called the killing ``a throwback to the old Afghanistan and a setback to the establishment of the new Afghanistan.''

Qadir's killing ``may indicate that we are going to have to be more of a participant in some of the security activities that are necessary in order to create a climate in which the new government can be established,'' Graham told NBC.

Senate Majority Leader Tom Daschle, D-S.D., said on CBS' Face the Nation that the slaying ``illustrates the degree of challenge we still have in Afghanistan. We have a long way to go to accomplish our goals.''