"anyone who voted for Obama did support gun control, whether they wanted to or not. By virtue of voting for him , they voted for his agenda and forthcoming agendas, whether they liked that particular part of his agenda or not."

Brian, I don't think voters anywhere buy the party-line letter, chapter and verse, particularly with omnibus bills where the controversial is slipped in with the promised to ram it through.

It is specious to say Obama voters support gun control "whether they wanted it or not"---in the sense gun control was their preference. It could have been of little significance compared to other reasons or the last thing on their minds.

As for abortion, it seems to me as much a litmus test for Republicans as Democrats. Similarly to gun control, I haven't noticed unanimity on the issue among liberals and conservatives there and here or in their parties.

Take a look at Wisconsin voters who elected presidential hopeful Scott Walker. Republicans there are divided by his activities, as all parties are from time to time, not least the Hilary supporters.

Voters holding their nose is common.