WASHINGTON -- Vice President Dick Cheney's daughter is reportedly pregnant.

The Washington Post said 37-year-old Mary Cheney, the openly gay daughter of Vice President Dick Cheney and wife Lynne, is due in late spring. The paper reported she and longtime partner Heather Poe, 45, are "ecstatic." Poe and Cheney have been together for 15 years, according to the Post.

There's been no formal announcement, but the paper quoted a spokeswoman as saying the vice president and Mrs. Cheney are eagerly looking forward to the arrival.

"The vice president and Mrs. Cheney are looking forward with eager anticipation to the arrival of their sixth grandchild," spokesman Lea Anne McBride told the paper.

The vice president's older daughter, Elizabeth, 40, went on leave as deputy assistant secretary of state before having her fifth child in July, the Post reported.

The paper reported that Mary Cheney was a key aide to her father during the 2004 re-election campaign. She is currently vice president for consumer advocacy at AOL.

It's likely that news of the pregnancy will bring the debate about gay marriage back into the spotlight. During her father's campaign, gay activists criticized Mary for not publicly supporting same-sex marriage, the paper reported. Dick Cheney reportedly said people "ought to be free to enter into any kind of relationship they want to" but also noted that he would defer to the president's policy.

President George W. Bush is not just against gay marriage, he actually supports an amendment to the U.S. Constitution banning same-sex marriages.