Before today, Herman Cain, Mitt Romney, and John Huntsman held the unique position of being the only GOP presidential hopefuls who hadn't signed a crazy anti-abortion pledge filled with all sorts of pie-in-the-sky promises—among them, a promise to defund Planned Parenthood, only select pro-life Cabinet appointees, and in general endow fetuses with every liberty but the right to vote (because what GOP candidate wants to encourage youth voting?).

Now, via CNN.com:

One month after sparking a controversy over his stance against abortion rights, Republican presidential candidate Herman Cain is signing a leading social conservative group's anti-abortion pledge.

Tuesday the businessman and former Godfather's Pizza CEO and radio talk show host put his name to the Susan B. Anthony List's "Pro-Life Presidential Leadership Pledge."

... In addition to Cain, Rep. Michele Bachmann of Minnesota, former House Speaker Newt Gingrich, Rep. Ron Paul of Texas, Texas Gov. Rick Perry, and former Sen. Rick Santorum of Pennsylvania have also signed the pledge.

It's not surprising but it is disheartening. Instead of distinguishing themselves from their opponents, it seems that every day the GOP presidential hopefuls clamor to assimilate in what is turning out to be an Amazing Race to the bottom.