Obama, campaigning here Thursday with former Democratic rival Hillary Rodham Clinton, criticized McCain's opposition to an equal-pay Senate bill, his support for conservative-leaning Supreme Court justices and his abortion-rights objections.
"I will never back down in defending a woman's right to choose," Obama said at a "Women for Obama" breakfast fundraiser.
McCain, the Republican from Arizona, planned a similar day Friday when he will meet with female business owners in Minnesota and then hold a women-oriented town-hall meeting in Wisconsin. Asked about women in an interview this week, McCain said he wants to "make sure that any barriers to their advancement are eliminated."
Obama makes similar remarks, but the two differ sharply on their approach to several key issues. Obama would require employers to expand family and medical leave, for example, while McCain said Thursday it should "be subject to negotiations between management and labor."
"Senator Obama believes that big government is the answer," he said.
Women, who tend to make their choices somewhat later than men in presidential races according to some surveys, have been a coveted group for decades. Previous elections have focused on "soccer moms" and "security moms," for instance.
Women have leaned Democratic in recent elections, while men have tilted Republican. The width of the "gender gap" can determine which party wins the White House.
Obama led McCain among women, 42 percent to 37 percent, in an Associated Press-Yahoo News poll conducted in June. McCain would be happy to stay that close, because President Bush narrowly defeated Democrat Al Gore in 2000 while losing women by a larger margin: 54 to 43 percent. In 2004, John Kerry won 51 percent of the female vote, to Bush's 48 percent.
Obama's campaign is largely directed at younger, single, well-educated women, many of whom support abortion rights and want the same pay and opportunities that men have in the workplace. His biggest hurdle, for now at least, may lie in his own party: placating Democratic women who backed Clinton and felt she was treated unfairly by the news media or even Obama himself.
Since defeating Clinton in the primaries, Obama's strategy has been to praise her heavily at nearly every stop, and to draw as sharp a distinction as possible with McCain on key issues.
On Thursday, Obama cited recent Senate legislation designed to counteract a Supreme Court decision limiting the time workers have to file pay discrimination lawsuits. Obama said McCain "thinks the Supreme Court got it right."
"He suggested that the reason women don't have equal pay isn't discrimination on the job - it's because they need more education and training," Obama said, eliciting groans from the audience.
Obama backed the Senate legislation that would have made it easier for women to sue their employers for pay discrimination. McCain opposed it, saying at the time: "I am all in favor of pay equity for women, but this kind of legislation ... opens us up to lawsuits for all kinds of problems."
McCain, who calls himself a "proud conservative," takes a much more hands-off approach to most regulatory issue, making it easy for opponents to accuse him of not using the government's powers to help struggling women. They point, for example, to his vote against a Senate amendment that would have required insurance companies to cover birth control products.
Many insurers cover products such as Viagra, prompting cries of unfair treatment by some women's groups.
Asked this week what he could do to attract more female voters, McCain said: "I don't have a specific policy at the moment, except to, again, I think my support of small business and the fact that I will not raise people's taxes. One of the greatest areas of participation of women in America is small business."
The two candidates differ sharply on abortion rights, which McCain has long opposed. Obama says McCain would appoint Supreme Court justices who would overturn the Roe v. Wade decision affirming a woman's constitutional right to an abortion.
"Senator McCain has made it abundantly clear that he wants to appoint justices like (John) Roberts and (Samuel) Alito," Obama said Thursday. "And that he hopes to see Roe overturned."
Underscoring his point, Planned Parenthood endorsed Obama this week. Given the two men's differences on reproductive issues, Obama told the breakfast audience, the group's decision was hardly "a nail-biter."