WASHINGTON — When it comes to his abortion record in Illinois, Senator Obama is taking flak from all sides.

First, Senator Clinton accused him of lacking political backbone in voting “present” on a bill that, according to abortion rights advocates, undermined the landmark Supreme Court ruling in Roe v. Wade. Now abortion foes are targeting him from the right over the same question: They say his opposition to legislation aimed at protecting infants born alive after a botched abortion demonstrates his extremism on the flash point social issue.

The conservative attacks have intensified in recent days, with opponents of legalized abortion sending out missives against Mr. Obama and a YouTube video circulating that casts his position on abortion as more extreme than even the most stalwart supporters of a woman’s right to choose, including Mrs. Clinton and Senator Kennedy of Massachusetts.

The presumptive Democratic nominee responded sharply in an interview Saturday night with the Christian Broadcast Network, saying anti-abortion groups were “lying” about his record.

“They have not been telling the truth,” Mr. Obama said. “And I hate to say that people are lying, but here’s a situation where folks are lying.”

He added that it was “ridiculous” to suggest he had ever supported withholding lifesaving treatment for an infant. “It defies common sense and it defies imagination, and for people to keep on pushing this is offensive,” he said in the CBN interview.

At issue is the Born Alive Infant Protection Act, a bill in the Illinois state Senate that sought to protect against bungled abortions by requiring that a fetus that survived an abortion be defined as a person. Fearing that the legislation could be interpreted more broadly to protect fetuses that were not yet viable — thus threatening Roe v. Wade, abortion rights advocates pushed for an amendment that explicitly limited the scope of the bill to infants “born alive.”

“Nothing in this section,” the added sentence reads, “shall be construed to affirm, deny, expand, or contract any legal status or legal right applicable to any member of the species homo sapiens at any point prior to being born alive as defined in this section.” A federal version with that added clause passed Congress unanimously in 2002, with the support of Mrs. Clinton and Mr. Kennedy, among others. Mr. Obama said in 2004 and again on Saturday that he would have supported the federal version.

During the Democratic primary, Mrs. Clinton’s campaign criticized Mr. Obama for voting “present” — instead of “no” — on the “Born Alive” bill in Illinois, which did not contain a provision protecting the Roe v. Wade decision.

The dispute flared again last week when a leading opponent of legalized abortion, the National Right to Life Committee, posted records from the Illinois Legislature showing that Mr. Obama, while chairman of a Senate committee, in 2003, voted against a “Born Alive” bill that contained nearly identical language to the federal bill that passed unanimously, including the provision limiting its scope.

The group says the documents prove Mr. Obama misrepresented his record.

Indeed, Mr. Obama appeared to misstate his position in the CBN interview on Saturday when he said the federal version he supported “was not the bill that was presented at the state level.”

His campaign yesterday acknowledged that he had voted against an identical bill in the state Senate, and a spokesman, Hari Sevugan, said the senator and other lawmakers had concerns that even as worded, the legislation could have undermined existing Illinois abortion law. Those concerns did not exist for the federal bill, because there is no federal abortion law.

In 2005, the campaign noted, a “Born Alive” bill passed the Illinois Legislature after another clause had been added that explicitly stated that the legislation would have no effect on existing state abortion laws.

Told of the campaign’s explanation, the legislative director of the National Right to Life Committee, Douglas Johnson, was dubious. “These are newly manufactured and highly implausible excuses,” he said. “There is no way that the bill would have had any effect on any method of abortion.” Mr. Johnson said the version Mr. Obama voted down clearly applied only to fetuses that emerged from the womb alive.

In addition to the outrage from abortion opponents, a five-minute YouTube video now making the rounds highlights Mr. Obama’s opposition to the legislation. The clip, which has been viewed more than 230,000 times, features a testimonial from Jill Stanek, a former nurse who spearheaded the push for the bill in Illinois after witnessing a live infant discarded and left to die at the hospital where she worked. Ms. Stanek appeared at the White House ceremony in 2002 when President Bush signed the federal bill into law.

The McCain campaign yesterday added its voice to the criticism of Mr. Obama. “Americans can differ on the issue of abortion, but Senator Obama’s extreme record on this issue and his willingness to misrepresent that record should concern any American who believes that we should be working towards a society where there are fewer abortions, not more,” a spokesman for Senator McCain, Brian Rogers, said.