DES MOINES, Iowa — Some Army National Guard units may have to deploy overseas without a chaplain if recruitment incentives, including $10,000 signing bonuses, don't work to fill hundreds of vacant positions.

Some chaplains have served repeated overseas tours to help take up the slack.

"We're all concerned that we don't wear the guys out — there is a limit," said Chaplain Lt. Col. Randall Dolinger, a spokesman for the Army Chief of Chaplains Office in Arlington, Va.

The Army National Guard has 310 chaplain vacancies.

That's 40 percent of its authorized level, but so far the Guard has not been forced to deploy units without a chaplain, Dolinger said.

Vacancies soared after 2001, when many chaplains moved to active duty in the Army. Filling the openings has been difficult because faith leaders have been deterred by the likelihood of long and repeated deployments to Iraq and Afghanistan, Dolinger said.

Complicating matters, chaplains aren't covered by a federal law protecting soldiers' jobs while they are deployed.

"A chaplain can't sue their church," Dolinger said.

And even those who want to serve as chaplains may not qualify. Candidates must pass a physical-fitness test, have a seminary or master's degree and be endorsed by a recognized denominational group. They also must complete counselor training and become certified in suicide prevention. An age range of 21 to 42 is occasionally lifted to fill large voids, such as the need for Roman Catholic priests.

The Guard has created a recruitment Web site, sent out promotional DVDs and hired 14 chaplain recruiters in the last year. They tout what the Guard can offer: a $10,000 signing bonus, a $20,000 student loan repayment plan and a $4,500 college scholarship.

The effort is seeing some success, with more than 90 new chaplains in the last year, said Chaplain Maj. Timothy Baer, the National Guard's chief of specialty branch recruiting.

"It's cooking the fire now and we're expecting some great things now," Baer said.

Filling the openings remains a challenge in some areas.

In Iowa, 10 of 17 chaplain positions are empty. General recruiter Jeff Lee, a chief warrant officer 3, said he makes about five contacts a month with potential chaplains and stresses the grants and sign-on incentives.

"Anytime you get a chaplain lead, you get right on it," said Lee, who is stationed in Johnston, Iowa.

Chaplains who have served in Iraq and Afghanistan describe a rewarding but exhausting experience. In addition to conducting services, they provide personal counseling, lead suicide prevention and post-traumatic stress group seminars and take the lead as cultural educator.