Former Pennsylvania Sen. Rick Santorum, who’s looking increasingly like someone running for the Republican presidential nomination, distributed a defiant message to supporters Saturday in defense of his comments comparing the anti-abortion movement to the civil rights struggles of African-Americans.

On Thursday, Santorum said in an interview with the Christian News Service that he was surprised by President Barack Obama’s support of abortion rights. “I find it almost remarkable for a black man to say, ‘We’re going to decide who are people and who are not people,'” Santorum said.

Santorum’s statement, which came roughly on the 38th anniversary of the landmark Supreme Court decision Roe v. Wade, produced a rash of criticism and media coverage. Santorum responded late Saturday morning by calling on supporters to push Obama to protect “the civil rights of the unborn.”

“For decades certain human beings were wrongly treated as property and denied liberty in America because they were not considered persons under the constitution,” Santorum wrote. “Today other human beings, the unborn of all races, are also wrongly treated as property and denied the right to life for the same reason; because they are not considered persons under the Constitution.”

Santorum has been out of elected office since losing his Pennsylvania Senate seat to Sen. Bob Casey (D) in 2006. Santorum has made no secret of his interest in the White House, having made several trips to New Hampshire and Iowa in recent weeks, apparently laying the groundwork for a presidential campaign.

Santorum also hired a New Hampshire coordinator for his political action committee earlier in the month.

Saturday’s message staunchly defended his connection of the anti-abortion movement to the civil rights movement.

“For decades, leaders on the right and left — from President Ronald Reagan to Rev. Jesse Jackson in the 1970s, to more recently Dr. Alveda King, niece of Dr. Martin Luther King, Jr. — have said that abortion is a civil rights issue,” Santorum wrote. “Data from the U.S. Centers for Disease Control only proves our point: 40 percent of abortions are performed on African-American women even though African-Americans make up just 13 percent of the U.S. population.”

He continued: “This weekend, as we remember the 38th anniversary of Roe vs. Wade, we have an opportunity to encourage President Obama and members of his party to recognize the rights of the unborn in this country.”

Santorum, long a favorite of social conservatives, gave his fundraising e-mail the subject line, “Political Correctness Run Amok.”

On Saturday, Obama issued a statement recognizing the Roe v. Wade decision, saying the ruling upheld the premise that “government should not intrude on private family matters.”

“I am committed to protecting this constitutional right,” Obama said. “I also remain committed to policies, initiatives, and programs that help prevent unintended pregnancies, support pregnant women and mothers, encourage healthy relationships, and promote adoption.”