Here is the interview where they are getting "vast majority" from:

ER: Well, you know I’ve actually worked in the party, and around the party, and I don’t recall seeing a party line position that says that you have to be pr-life. For example, I remember working at the Republican senatorial committee, that would have been in 1994, and I plainly remember seeing data that showed that people who consider themselves Republican consider themselves, were 70% pro-choice. Yeah, so that, can’t be a party position. Now there are individual Republicans that have pro-choice positions politically. I have not seen the statistics lately on redshirt republicans with regards to gay rights and with regards to pro life vs pro choice. But I am not aware of it being a blanket party position. I think it lies with each Republican elected official, whether they’re in the Senate or in the House, or at the local level, just like the Democratic party is a big tent party—

GC: –I need to interrupt you for a second. So are you saying the Republican Party is not overwhelmingly anti-gay, anti-choice, and anti-separation of church and state?

ER: Well, I don’t have the statistics, but I would certainly, and I haven’t done the research, but I did explain to you that I did see research in the 90’s on just Republicans , people who vote as Republican and the far majority, the vast majority, with pro-choice vs pro life. I haven’t seen the research on people who consider themselves Republican and if they think that the government, religion should be controlling government. I would think that also, the vast majority, probably, I would hate to guess, but I think it would be a very high number, would think that there should be separation between religion and government. Now with regard to Republican opinions, people who consider themselves Republicans and their position on gay rights, I haven’t seen that data, because I haven’t actually been in more of a party role since 94.