ST. PAUL, Minn. — The Republican presidential nominee, Senator McCain, began his final drive for the White House today with a boost from running mate Governor Palin while Democratic opponent Senator Biden declared her family “off limits” and suggested that some news media coverage of her had been sexist.

Ms. Palin and her husband, Todd, announced this week that their 17-year-old unmarried daughter was pregnant and would be marrying her boyfriend, saying they were making a private matter public because of Internet rumors. Mr. Biden said the Democratic campaign was not attacking Ms. Palin over her family.

“It is off limits to talk about her family,” Mr. Biden said in an interview with “Fox and Friends” on Fox News Channel. “Every family has difficulty as they’re raising their children. I think the way she’s handled it has been absolutely exemplary.”

The Palins have five children, including a 4-month-old son with Down syndrome, which has sparked widespread discussion over whether Ms. Palin could balance her family responsibilities with the duties of vice president.

Asked if some of the criticism aimed at Ms. Palin has been sexist, Mr. Biden said: “Yes, by you guys in the media. … When I heard that media response, you know, this coming from some of the right-wing guys, saying that, ‘Well, how can you be a mother and a vice president at the same time?’ … I mean, millions of women in America are going through exactly what she (is going) through. And guess what? They can handle it.”

Meanwhile, Mr. McCain’s wife, Cindy, said she doesn’t agree with Ms. Palin’s opposition to abortion in cases of rape and incest. She also parts ways with Ms. Palin on sex education.

Ms. Palin opposes abortion and rejects the view that pregnancies caused by rape and incest should be exceptions.

“I don’t agree with that aspect, but I do respect her for her views,” Ms. McCain told ABC’s “Good Morning America” in an interview taped for broadcast Thursday.

Ms. Palin has opposed funding sex-education programs in Alaska. However, Ms. McCain told ABC that she advocated abstinence as a part of sex education at her children’s school. “I believe that it’s twofold and I think all of it should be taught,” she said.

In a prime-time acceptance speech at the Republican National Convention, Ms. McCain was expected to review his career in public service — first as a Naval Academy midshipman and wartime pilot and then as a 26-year veteran of Congress — while drawing stark policy differences with the Democratic candidate, Senator Obama.

Democratic critics have questioned Palin’s political experience as a small-town mayor and her brief tenure as Alaska’s governor, but she turned the tables last night by offering a searing, sometimes sarcastic attack on the opposing ticket.

Mr. Biden complimented Ms. Palin for delivering an impressive speech with skill but said that issues important to Americans were missing from her remarks.

“I didn’t hear the phrase ‘middle class’ mentioned, I didn’t hear a word about health care. I didn’t hear a single word about what we’re going to do about the housing crisis, college education, all the things that the middle class is being burdened by now,” Mr. Biden told CBS’ “The Early Show.”

“There was a deafening silence about the hole that the Republicans have dug us into and any specific answers as to how the McCain-Palin ticket is going to get us out of that hole,” Mr. Biden said.

Mr. McCain’s speech was expected to provide the climax to the four-day convention at the Xcel Energy Center. His wife, Ms. McCain, admitted that she was nervous about addressing delegates herself.

“I’d like people to know what makes me work and what makes me tick and who I am, what I’m all about and where I come from,” Ms. McCain told ABC. “I have an interesting story to tell as well in that it combines the two of us and makes us a couple and what we will represent.”

Ms. Palin joined other Republican speakers last night in praising Mr. McCain as a man of character, a former Vietnam prisoner of war who had spent his early career in the military and had sought to change the ways of politics in Washington.

“In politics, there are some candidates who use change to promote their careers. And then there are those, like John McCain, who use their careers to promote change,” Ms. Palin, toying with the central theme in Mr. Obama’s campaign, said.

Ms. Palin’s 19-year-old son, Track, ships out for Iraq next week with his Army unit. The governor was unflinching as she contrasted Mr. McCain’s military record with a lack of armed service by Messrs. Obama and Biden.

“There is only one man in this election who has ever really fought for you in places where winning means survival and defeat means death — and that man is John McCain,” she said.