Addressing a meeting of Planned Parenthood, Mr. Obama singled out lawmakers in North Dakota, Mississippi and, by implication, the nation’s capital for proposing and in some cases enacting “absurd” laws that he said would return the country to the days before the Roe v. Wade decision guaranteeing abortion rights.

“When you read about some of these laws, you want to check the calendar,” Mr. Obama said. “You want to make sure you’re still living in 2013. Forty years after the Supreme Court affirmed a woman’s constitutional right to privacy, including the right to choose, we shouldn’t have to remind people that when it comes to a woman’s health, no politician should get to decide what’s best for you.”

Mr. Obama was originally scheduled to address the group on Thursday but had to postpone his appearance to attend a memorial service in Texas for firefighters killed in a fertilizer plant explosion last week. Rather than pass off the obligation to another member of his administration, Mr. Obama asked the group to let him come a day late so he could speak out on an issue that galvanizes his liberal political base.

The president’s speech came at a time when several states have passed restrictive new abortion laws, and not long after a furor in Congress in which some Republicans objected to administration policies intended to ensure that insurance companies cover contraception.

North Dakota just enacted a law banning abortion when a heartbeat can be detected, as early as six weeks into a pregnancy. Arkansas this spring similarly banned most abortions at the 12th week of pregnancy. In Mississippi, conservatives tried to ban all abortions, only to have their effort rejected in a referendum in 2011. In Washington, some Republicans have questioned federal financing for Planned Parenthood because it provides abortion services, among other health care services.

Abortion opponents have also drawn attention lately to the trial of a Philadelphia doctor charged with killing viable fetuses during abortions. Three of seven murder charges against the doctor, Kermit Gosnell, were thrown out by a judge this week, but the grisly details of the case have, in the view of abortion opponents, highlighted the moral questions underlying abortion in the United States.

An antiabortion group said a local Planned Parenthood group had been aware of complaints about Dr. Gosnell but did not intervene. The Philadelphia Daily News quoted the local group’s leader as saying that women had complained to the group about conditions at Dr. Gosnell’s clinic, and that the group would encourage them to report their complaints to the health department.

“President Obama blatantly ignored this inconvenient truth about the abortion industry’s horrific lack of oversight and disparaged the pro-life advocates who wake up each morning with the goal of saving the lives of unborn children and women from the pain of abortion,” said Marjorie Dannenfelser, the president of the Susan B. Anthony List, an antiabortion group.

Mr. Obama did not mention the case but condemned lawmakers who have targeted Planned Parenthood. “When politicians try to turn Planned Parenthood into a punching bag, they’re not just talking about you, they’re talking about the millions of women who you serve,” he told the group’s gathering, at a Washington hotel. “And when they talk about cutting off your funding, let’s be clear they’re talking about telling many of those women you’re on your own.”

He pledged his loyalty to the group. “You’ve also got a president,” he said, “who’s going to be right here with you fighting every step of the way.”