As polls tighten in the race to fill the Ohio Senate seat being vacated by Sen. Rob Portman, the two leading Republican contenders are swiping at each other’s anti-abortion bona fides as they jostle to lock down the conservative base.

Businessman Mike Gibbons, who has captured the lead in recent polling, cut an ad last Thursday bashing rival Josh Mandel for “flip-flopping” on abortion as he tries to stave off flak for supposedly being “squishy” on abortion in the past.