Stretched thin by the wars in Iraq and Afghanistan, the U.S. Army is considering a National Guard (search) and Reserve policy shift that could result in part-timers being called to active duty multiple times for up to two years each time, a senior Army official said.

The official, who discussed the matter with a small group of reporters on condition of anonymity because the matter has not been fully settled inside the Pentagon, said Thursday the Army probably will ask Defense Secretary Donald H. Rumsfeld (search) in the next several months to change the policy.

The official also said it appeared likely that the Army will ask Congress to permanently increase the statutory size of the Army by 30,000 soldiers, to 512,000. He said that decision would be made next year.

The Army has the authority to add 30,000 soldiers, but arranged for it to be only a temporary boost because it did not want a long-term commitment to the cost of a larger force. But now it appears that the Army has no choice but to accept a permanent increase, the official said.

The Army estimates that a permanent increase of 30,000 soldiers will cost it about $3 billion a year.

One reason that the National Guard and Reserve have been used so heavily over the past three years is that the active-duty Army is too small to meet the demands of war — particularly in Iraq (search), where troop levels have far exceeded original predictions — while also maintaining a presence in traditional areas of influence such as Europe and the Korean peninsula.

The Army now has about 660,000 troops on active duty, of which about 160,000 are members of the Guard and Reserve.

The Army wants them to be eligible for an unlimited number of call-ups, so long as no single mobilization lasts more than 24 months, the official said.

Under current policy set by Rumsfeld, a Guard or Reserve member is not to serve on active duty for more than 24 total months. Thus, for example, if a Guard or Reserve member was mobilized for six months after the attacks of Sept. 11, 2001, and later for nine months in Afghanistan, then that person is off limits for duty in Iraq because a yearlong tour there would exceed the 24-month limit. A standard tour in Iraq, for both active-duty and reserves, is 12 months.

If the limit were set at 24 consecutive months, with some break between tours, then in theory a Guard or Reserve member could be mobilized for multiple 12- or 24-month tours in Iraq or elsewhere.

That is the kind of flexibility the Army has decided it needs in order to sustain the forces needed in Iraq and Afghanistan, the official said. He stressed that the Army would make only sparing use of the authority to call up soldiers for longer tours because it would not want to alienate soldiers.

The National Guard, with about 350,000 members, and the 200,000-strong Reserve already are seeing signs of a slide in recruiting and retaining soldiers. Some may question whether a policy change that results in longer mobilizations could further erode the Guard and Reserve's ability to attract new soldiers and keep the ones it has.

The Guard in particular has been used so much in Iraq and Afghanistan that the Army now has deployed — or put on notice of plans to mobilize in 2005 — all 15 of its main combat brigades.