John McCain’s running mate, Sarah Palin, made a startling announcement Monday when she told the world her 17-year-old unmarried daughter is pregnant.

Her daughter, Bristol, plans to keep the baby and will marry the baby’s father, Palin said.

"Our beautiful daughter Bristol came to us with news that as parents we knew would make her grow up faster than we had ever planned. We’re proud of Bristol’s decision to have her baby and even prouder to become grandparents. As Bristol faces the responsibilities of adulthood, she knows she has our unconditional love and support," Sarah and Todd Palin said in a statement released by the McCain campaign Monday.

"Bristol and the young man she will marry are going to realize very quickly the difficulties of raising a child, which is why they will have the love and support of our entire family. We ask the media to respect our daughter and Levi’s privacy as has always been the tradition of children of candidates."

The Alaska governor also announced she hired a lawyer in Alaska to investigate the firing of her public-safety commissioner — a firing she has come under much scrutiny for in her home state — as state legislators investigate whether she may have abused her power in firing the official for refusing to fire her ex-brother-in-law, a state trooper. CNN confirmed that Palin hired the attorney three weeks ago.

On the pregnancy news, McCain said he was aware of Bristol Palin’s pregnancy before he chose her mother for his running mate. Top McCain adviser Doug Holtz-Eakin told CNN that Palin "was completely vetted by the campaign" before she was chosen. The GOP senator’s advisers said McCain knew about the baby even before Palin told him during one of their "private conversations" last week, before he officially asked her to be on his ticket.

"Sen. McCain knew this and felt in no way did it disqualify her from being vice president," another aide told CNN. "Families have difficulties sometimes and lucky for her she has a supportive family."

Arthur B. Culvahouse Jr., the lawyer who conducted the vice-presidential search, told the AP that Palin also told the campaign about her husband’s two-decade-old DUI arrest during questioning as part of the vetting process, and provided lawyers with many details about the public-safety-commissioner firing and ensuing investigation.

Palin underwent a "full and complete" background examination before McCain chose her as his running mate, Culvahouse said. Asked whether everything that came up as a possible red flag during the review already has been made public, he said: "I think so. Yeah, I think so. Correct."

McCain adviser Nicolle Wallace told ABC’s "Good Morning America" on Tuesday that the McCain campaign had been forced to reveal Bristol’s pregnancy publicly Monday because of "lewd and outrageously false rumors" spread by "Democratic-leaning blogs and a few in the mainstream" media.

Sen. Barack Obama told the media to "back off" reporting on candidates’ families.

"I have said before and I will repeat again: I think people’s families are off-limits," the Democratic presidential hopeful said. "People’s children are especially off-limits. This shouldn’t be part of our politics. It has no relevance to Gov. Palin’s performance as a governor or her potential performance as a vice president. So I would strongly urge people to back off these kinds of stories."

CNN.com also reports that key evangelical leaders rallied to support Palin after the pregnancy news.

"Before, they were excited about her, with the Down syndrome baby," conservative, anti-tax activist Grover Norquist said. "But now with this, they are over the moon. It reinforces the fact that this family lives its pro-life values."

The Washington Post reports that the news makes it even harder to determine how women voters will react at the polls.

"Who knows how this will bounce around politically?" Democratic strategist Jim Jordan told the Post. "It’s just a lot for voters to absorb, the thought of both the vice president and her daughter with infants in the Naval Observatory."