PHOENIX (AP) - Senators from border states with Mexico are urging President Bush to extend the National Guard deployment, rather than let it expire next summer.

Already, half of the 6,000 National Guard troops sent to help secure the border with Mexico are gone with the rest leaving next summer, as planned.

"Americans could rightly question why the administration has dedicated 160,000 National Guardsmen to maintain order and security in Iraq, while eliminating the less than 6,000 Guardsmen performing an important task on our own southern border, which most agree is in a state of crisis," Sen. Jon Kyl, R-Ariz., wrote in July to President Bush. Sens. Dianne Feinstein, D-Calif., and Pete Domenici, R-N.M., also signed the letter.

Officials did not return calls about whether the mission should continue.

"Everyone agrees the border must be secured," said Maj. Paul Babeu, who commands Operation Jump Start's Task Force Yuma. "We at the Guard are a critical component in securing that border. The right thing to do is to continue that job until the Border Patrol believes it can sustain the mission without our support."

Border Patrol agents have said for months that they appreciate the help.

Since arriving at the border, guard task forces have allowed more Border Patrol agents to patrol rather than do clerical work. National Guard troops also are stationed in strategic observation areas that steer smugglers toward more remote areas. That gives agents time to intercept border crossers, authorities said.

Another Arizona task force has further slowed crossers by erecting fences and vehicle barriers.

And backers of keeping the guard at the border say Border Patrol agents can reach smugglers faster because another task force has constructed roads and improved damaged ones along the international line.