As for the Bosnians, I believe most are Muslim as well so that probably would explain them going for Obama as the GOP are pretty unpopular amongst Muslims regardless of where they come from. Not because Obama is Muslim (as most Muslims know he is not) but rather Islamophobia is quite rampant in the GOP so it would be pretty tough to vote for a party that is anti-Islam if you were a Muslim.
Only about 40% of Bosnians are Muslims. I think most in America are actually atheists (another very pro-Obama group). If they're not Muslim or atheist, they're probably Catholic.
Do you mean Bosnians or Bosniaks?