Bush was opposed to homosexual marriage/civil unions.
Actually, Bush supported civil unions before the 2004 elections.
Bush's gay union stance irks conservatives. The only difference between his position and Rudy's is that Rudy opposes a constitutional amendment to ban gay marriage.
The amnesty thing didn't come up until the second term.
But he did campaign on the issue both in 2000 and 2004. And he was about to come with an amnesty plan when 9/11 prevented that.
If he were running right now, I would oppose him on those grounds as well.
You would vote for him in the general election, and that's what matters.