NARAL then issued a statement praising him for his defense of the "core values" of the Democratic Party.
"It was stunning," Day said of Perez's about-face. "He goes out, and the DNC is behind this pro-life candidate, which is necessary to be a big tent party if we're going to win. So they rally behind this guy (Mello), and then less than 24 hours later he (Perez) puts a statement out saying 'just kidding. We don't want you in the party at all.'"
Perez made the abortion issue "non-negotiable" for Democrats, Day continued, and was "strong-arming" party members "to step away from their conscience and not support the pro-life position anymore."
Democratic political leaders had mixed reactions to Perez's comments. On NBC's Meet the Press on Sunday, House Minority Leader Nancy Pelosi was asked if she thought there was room in the Democratic Party for pro-life politicians, she answered "of course."
Sen. Dick Durbin (D-Ill.), meanwhile, said on CNN on Sunday that he and the party were committed "to reproductive rights," and added that "I know within the ranks of the Democratic Party there are those who see that differently on a personal basis, but when it comes to the policy position, I think we need to be clear and unequivocal."
The 2016 Democratic Party platform featured a strong pro-abortion plank, calling not only for abortion access but also for the overturning of decades-old policies that prohibited direct taxpayer funding of abortions both at home and abroad – the Hyde Amendment and the Helms Amendment.
"We believe unequivocally, like the majority of Americans, that every woman should have access to quality reproductive health care services, including safe and legal abortion – regardless of where she lives, how much money she makes, or how she is insured," the platform stated.
"We will continue to oppose – and seek to overturn – federal and state laws and policies that impede a woman's access to abortion, including by repealing the Hyde Amendment."
Pro-lifers, meanwhile, have countered that NARAL's pro-abortion strategy alienates millions of Democratic voters.
"Pro-life Democrats have been leaving in droves," Day said of recent elections. Perez's total support for abortion rights "may be popular in California or New York," she said, but "these values don't play well in the heartland."
"There is an enormous disconnect between Democrat and Independent rank and file voters and national leaders like DNC Chairman Tom Perez and Senator Dick Durbin on the issue of abortion," said Marjorie Dannenfelser, president of the pro-life group Susan B. Anthony List.
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Dannenfelser was one of the pro-life advisors to the Trump campaign in the 2016 election, heading the campaign's pro-life task coalition.
Perez "drew a line in the sand" with his comments on Friday said Jeanne Mancini, president of the March for Life, adding that he was "decisively alienating the 23 percent of Democrat voters who identify as pro-life and 44 percent of Democrats oppose taxpayer funding of abortion."
"The March for Life has a 44-year track record of uniting people of all backgrounds in defense of the inherent dignity of all human life," she said.
"We have welcomed and will continue to welcome pro-life Democrats like Rep. Dan Lipinski (D-IL) to speak at the March, and will continue to support all whom fight for the right to life until the culture of abortion is unthinkable to every person and party alike."