ST. PAUL, Minn. — Republicans are warning Democrats that if they attack Governor Palin’s family over the disclosure that the 17-year-old, unmarried daughter of Senator McCain’s running mate is five months pregnant, they do so at their own peril.

Despite comments from Senator Obama today urging the press to “back off” from stories about Bristol Palin, Republicans predict the attacks will be coming from Democrats in general and affiliated independent groups.

Senator Coleman, a Republican from Minnesota, said Democrats would attack the issue of the younger Palin’s pregnancy at their own risk. “Americans will look in their own mirror; we all have that issue somewhere in our family,” he said.

“It is part of her humanness, her connection to people. That is what it is,” Mr. Coleman said. “Certainly it will not impact on her ability to govern. She is standing with her daughter in some challenging times. I think that’s great.”

Senator Hatch, a Republican from Utah who is one of the leaders of the social conservative caucus, said he thought the press’s fascination with the story was “despicable.” “She is a young girl. All parents have some difficulty with children,” he said. “It’s a family matter, it is a personal matter. She’s not running for anything. I think it’s a tribute to Sarah Palin that she is as open and forthright as she is. Frankly, it’s despicable to make an issue of this.”

The former lieutenant governor of Maryland, Michael Steele, said, “I know the Democrats are salivating, wanting to make a big deal out of this. But this is America, this is an American family, it happens in America all the time. They will do what they need to do. We leave it to them. I think the attacks will come, and the push-back will be, what family do you know that hasn’t had to deal with this or other issues?”

The disclosure that Governor Palin was soon to become a grandmother seemed aimed in part at dispelling lurid speculation elsewhere on the Internet about the Palin family.

In a statement to the press Monday, Governor Palin and her husband, Todd,asked the press to respect the privacy of their daughter, Bristol, whom they said planned to marry the father of the child. “We have been blessed with five wonderful children who we love with all our heart and mean everything to us. 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,” the statement said.

Advisers to the McCain campaign yesterday said that the senator knew of Bristol Palin’s pregnancy before making his decision to pick Governor Palin as his running mate. In some ways the news that the daughter of the Republican ticket’s vice presidential candidate will have a child has been greeted with excitement from the grass roots.

Charcie Russell, a McCain delegate from Castle Rock, Colo., whose first choice in the Republican primary was her congressman, Tom Tancredo, said, “We are glad they are going to be married. This is a family who loves life. We like the idea of a child that is going to have a mother and a father.” Mrs. Russell’s co-delegate, Krista Huff, said, “When the Palin pick was announced, I was so happy I put on a dress. Mrs. Russell, Mrs. Huff, and their fellow delegate Keri Brehm wore T-shirts that read together: “Moms Trust McCain.”

Reuben Jimenez, a McCain delegate from Fort Worth, Texas, said he was not concerned about the pregnancy, and said it was no reason for Governor Palin to drop out of the race. “No. This happens to a lot of families. The lucky thing for this baby is that it will be Sarah Palin’s grandson.”

While the news broke about Bristol Palin, behind the scenes the McCain campaign was putting together a policy brain trust for Governor Palin. Rep. Peter King, a Republican from New York, said he wanted to know whether Governor Palin believed as he did in “American exceptionalism.” “I want to know if she knows that we need to be a leader in the world, whether we like it or not,” he said, adding that he hopes, “she realizes the importance of expanding the international infrastructure we set up in terms of dealing with terrorism.”

Senator Coleman said that he was not worried about Governor Palin’s views on foreign affairs. “It is going to be a McCain administration, and I am very comfortable with John McCain on national security issues,” he said.

Governor Palin is scheduled to address the convention on Wednesday. On Thursday, Mr. McCain is scheduled to accept his party’s nomination for the presidency.