Why Did Heidi Heitkamp Flip-Flop on Late Term Abortions?

Congressman Kevin Cramer’s Senate campaign has a new ad out today hitting his opponent, incumbent Heidi Heitkamp, on her support for late-term abortions.

It’s a provocative spot, featuring two of Kevin’s daughter’s, one of whom is visibly pregnant and says it looked like Heitkamp was celebrating the defeat of a late-term abortion ban on the floor of the Senate when she did that now-infamous high-five with Senate Minority Leader Chuck Schumer:

But more interesting than the ad is something The Atlantic mentioned in reporting about it. I had forgotten this, but during the 2012 election cycle Senator Heitkamp said that late-term abortions should be illegal. Yet she voted against a federal ban on late term abortions, and when asked about her apparent change of heart by the news media she refused to answer:

During her first Senate campaign in 2012, Heitkamp argued that late-term abortion should be illegal “except when necessary to save the life of the mother.” Yet in 2015, she voted to filibuster a bill that would ban abortions after the fifth month of pregnancy. As The Weekly Standard’s John McCormack reported at the time, when he attempted to ask about her seeming change of heart, Heitkamp “refused to talk about it.”

Shouldn’t the Senator speak, before her constituents, about this significant shift on a hot button issue?

I understand that the abortion issue isn’t everyone’s cup of tea, but a lot of people care about it. If the Senator has had a change of heart from the position she’s articulated in past campaigns, she should explain it.