WASHINGTON -- Vice President Dick Cheney's daughter Mary delivered an 8-pound, 6-ounce baby boy on Wednesday, the first child for her and her female partner of 15 years, Heather Poe.

Survey: Daughter For Mary Cheney?

Samuel David Cheney was born at 9:46 a.m. at Sibley Hospital in Washington, the vice president's office announced. Vice President Cheney and his wife, Lynne, paid a visit to their new -- and sixth -- grandchild a few hours later.

Mary Cheney announced in December that she and Poe had decided to start a family. Her decision to become pregnant and raise a child with Poe was criticized in some conservative circles.

James Dobson, founder of Focus on the Family, asserted that children need to be reared by heterosexual married couples, for instance.

"With all due respect to Cheney and her partner, Heather Poe, the majority of more than 30 years of social-science evidence indicates that children do best on every measure of well-being when raised by their married mother and father," he wrote in Time magazine.

"That is not to say Cheney and Poe will not love their child. But love alone is not enough to guarantee healthy growth and development. The two most loving women in the world cannot provide a daddy for a little boy -- any more than the two most loving men can be complete role models for a little girl."

The vice president bristled at questions on the topic, even though President George W. Bush and Republican candidates asserted their opposition to gay marriage in recent election cycles.

Campaign rhetoric aside, the president said he believed Mary Cheney and her partner would make loving parents.

Mary Cheney was an aide to her father during the 2004 campaign and now is vice president for consumer advocacy at AOL.