Obama went from losing it by 2.38% to losing it by 13.64%
Montana is a libertarian leaning state. Perot did extremely well there. So in 2008, due to the Iraq War and Bush's social conservatism, along with Ron Paul being on the ballot there as a write-in candidate, Obama managed to do well. But Obama's big-government liberalism, Obamacare, stimulus, did not resonate well with Montana in 2012.
Paul only got 2.17% if you give McCain all of Pauls votes his lead would only go from 2.38% to 4.55% which is one third of Romney's lead of Obama in Montana