The request, sent to lawmakers this week, would apply to all active duty branches of the military services, said Air Force Lieutenant Colonel Ellen Krenke, a Pentagon spokeswoman, on Friday.
But it is aimed chiefly at the active duty army, which has fallen far short of recruiting goals this year, by adding millions of potential enlistees.
Missing recruitment goals
The army has provided most of the 140,000 US ground troops in Iraq and has also relied heavily on part-time soldiers from the National Guard and Reserve for year-long deployments there.
Krenke said the active duty Air Force, Navy and Marine Corps, which are meeting their recruiting goals, were unlikely to change their current policy of declining to accept recruits older than 35.
The new proposal would not change the limit of 39 years for those with previous military service who seek to enlist in the Army Reserves and National Guard.
The Army National Guard, struggling more than any other part of the US military to sign up new troops amid the Iraq war, missed its ninth straight monthly recruiting goal in June.
The regular army met its recruiting goal this month, but is still 14% behind its year-to-date recruiting target and is in danger of missing an annual recruiting goal for the first time since 1999. The Army Reserve is 21% behind its year-to-date goal and also in danger of falling short for the year.