The following comes from a November 12 Weekly Standard article by John McCormack: 

On Tuesday, the New York Times reported that Right to Rise, a super PAC set up by Jeb Bush, has produced but not yet aired a TV ad attacking Marco Rubio as unelectable because of his pro-life stance. Rubio said in an August debate that he “never advocated” for exceptions to abortion restrictions in the cases of rape or incest, even though every significant piece of pro-life legislation in Congress includes those exceptions.

Ashley Parker of the New York Times reports:

[O]n Wednesday, when asked, Mr. Bush declined to personally criticize Mr. Rubio’s hard-line stance on abortion.

“Look, I don’t think anybody should be critical of someone who’s pro-life, because I’m the most pro-life candidate on that stage,” he said.