I would say homosexuality. Although, some staunch conservatives say that we already have a Muslim in Office right now, which I vehemently disagree with. The muslim religion is, for better or for worse, linked to terrorism and unlike the views of my good friend Sally Kern, homosexuality is not a worse threat than terrorism. Terrorists can kill, homosexuals probably will just vehemently disagree, they won't kill. At least, the GLBT's I've known aren't violent people, terrorists do.
I haven't read too much about President Buchanan, other than that he was arguably the worst president, if not of history, then definitely the 19th century.
No, he isnt muslim, but he sympathizes with their cause and gives aid and comfort to the enemy. He apologizes for our country constantly and includes them as if they are part of the main American makeup along with Judaism and Christianity.
There are a couple million Muslims living in America, who are proud American citizens. They are part of the American makeup along with Christians and Jews, as well as people of other religions.
And he (I assume you mean Obama) does not sympathize with terrorists and provide them with aid and comfort. He is going around "apologizing" for our country because Bush has spent the last eight years sullying our image to the world. That's not to say Obama's foreign policy is any different.