But my question remains. Would a Democrat voter vote for a Republican candidate and vice versa?

Well Rain Dog (cool screen name BTW) I can only speak for myself in that regard. When I was 15 I got the chance to tour Europe with the School Band of America as a last-minute replacement, but it hinged on being able to get a passport in a hurry. My parents contacted our congressman and 2 days later a government car pulled up in front of my house with my passport. Six years later when I voted for the first time he happened to be on the ballot and I felt like I owed him one. That's the only time in my life I ever voted for a Republican. It isn't personal, it's just that in order to be a Republican candidate you must support policy that I find detrimental to us as citizens. And that becomes increasingly true with every new bunch. The last decent president from that party was probably Eisenhower, but had I been around then I still would have been "Madly for Adlai".