WASHINGTON — Senator Clinton is going after Senator Obama’s record on abortion rights, but on at least one measure, she may be holding him to a tougher standard than she holds herself.

Senator Clinton’s campaign in recent days has ratcheted up its criticism of Mr. Obama’s voting history in the Illinois state Senate, citing seven instances in which he voted “present” instead of “no” on bills that were seen as infringing on a woman’s right to choose.

Yet one of those bills — the “Born-Alive Infants Protection Act” — is similar to legislation that Mrs. Clinton and 97 other senators supported in Congress in 2001. The federal measure, sponsored by a leading abortion foe, Senator Santorum of Pennsylvania, was intended as a protection against botched abortions and required that a fetus that survived an abortion be defined as a person.

The federal legislation defines a person “born alive” to mean “the complete expulsion or extraction from his or her mother of that member, at any stage of development, who after such expulsion or extraction breathes or has a beating heart, pulsation of the umbilical cord, or definite movement of voluntary muscles, regardless of whether the umbilical cord has been cut, and regardless of whether the expulsion or extraction occurs as a result of natural or induced labor, caesarean section, or induced abortion.”

Mr. Obama voted “present” on legislation in 2001 that contained nearly identical language as part of what he and his supporters have described as a strategy engineered by abortion rights advocates. The effort was designed to rebuff attempts by anti-abortion legislators to paint Democratic lawmakers as extremist by forcing them to vote against legislation involving “live birth” abortions.

Leading abortion rights groups, including NARAL and Planned Parenthood, did not oppose the federal legislation, citing additional language that made clear that the bill would have no impact on Roe v. Wade, the 1973 Supreme Court decision forbidding states from banning abortion. “Nothing in this section,” the added sentence in the federal version 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.”

President Bush signed the federal “born alive” bill into law in 2002 after its unanimous approval in the Senate, while the Illinois version failed to pass.

The Clinton campaign said the distinction between the federal and the state measure was clear. “Senator Clinton backed a bill that had specific protections for Roe v. Wade. Senator Obama voted present on a bill that had no protections for Roe,” a spokesman, Blake Zeff, said. “That’s a rather significant difference.”

Mr. Obama spoke out against the Illinois bill when it was debated in the state Senate in 2001, testifying that he was voting “present” because he thought he would not pass “constitutional muster” as a restriction on abortion. He voted “no” on a similar version of the measure when it came up in 2002.

He also argued in 2004 that the state and federal bills were substantively different, telling the Chicago Tribune that he would have voted for the “born alive” bill had he been in Congress at the time.

An anti-abortion advocate who testified before Congress and before Mr. Obama’s committee in the Illinois Senate, Jill Stanek, sees it differently, saying that Mrs. Clinton and the abortion rights community were overstating the distinctions in the legislation. “Clinton is being so audacious trying to claim that Obama is less pro-choice when on the very same bill she voted pro-life,” Ms. Stanek said. “It’s just astounding.”

Ms. Stanek, a registered nurse from Illinois who pushed for the passage of the “born alive” bill, said argued that the language in the federal does not add protection for Roe v. Wade but was more palatable for abortion rights advocates to accept.

The “born alive” issue has surfaced amid an escalating back-and-forth between the Clinton and Obama campaigns over his Illinois voting record. Aides to Mrs. Clinton say his “present” votes are part of a pattern of lackluster leadership as a legislator in which he dodged tough votes for political convenience. They point to 129 such votes during his time in the Illinois Senate, including many in which he was the only legislator voting “present.”

Mr. Obama’s supporters say the attacks are an attempt to create a wedge issue between two candidates with 100% “pro-choice” records. His campaign yesterday sent out a mail piece to Nevada voters hitting back at Mrs. Clinton, saying her “false attacks won’t protect a woman’s right to choose.”

Most of Mr. Obama’s “present” votes in Illinois, his campaign says, were part of a legislative strategy or were cases in which he doubted the constitutionality of a bill.

“For us, a ‘present’ vote was a ‘no’ vote,” the president of the Illinois chapter of Planned Parenthood, Pam Sutherland, said. “We in Illinois considered Barack Obama a pro-choice leader.”

She said the “born alive” bill was part of a package of three measures introduced by anti-abortion lawmakers. The other two were more expansive, she said, and would have put a “chill” on doctors who performed abortions. One would have required a second physician to be present during any abortion procedure where there was a “reasonable” chance that a fetus would be born alive, and the other would have covered medical costs for the parents of a fetus born alive. The strategy for abortion rights supporters, she said, was to vote “present” on all three bills.

An e-mail from the Clinton campaign this week pointed reporters to the Illinois National Organization for Women, whose president, Bonnie Grabenhofer, was quoted in the Clinton e-mail as saying that on the “born alive” bill in the Illinois state Senate, “When we needed someone to take a stand, Senator Obama took a pass.”