WASHINGTON, April 1 (UPI) -- The Pentagon balked at U.S. Rep. Tammy Baldwin's domestic partner accompanying her on a military flight for a congressional trip to Europe, officials said.

The Politico reported Tuesday that House Speaker Nancy Pelosi intervened before Congress' Easter break so the Wisconsin Democrat, the only openly lesbian member of Congress, could be joined by her partner.

The Web site reported that House rules allow members of Congress to take their spouses with them on military flights if there is room for them and when it is "necessary for protocol purposes."

But the Defense Department did not consider Lauren Azar a "spouse."

Pelosi reportedly urged Defense Secretary Robert Gates to follow the precedent established by former House Speaker Dennis Hastert, R-Ill., who allows Azar to accompany Baldwin on trips.

Gates said he would allow Azar to travel on a military plane if Pelosi sends him a letter authorizing the trip.

"This is not an issue of DOD regulations," said Pentagon press secretary Geoff Morrell. "Secretary Gates honored a request from Speaker Pelosi to make an exception to the House rules.

"But that's really as far as it goes."