Wow, I typed an unique for an! essay and then Word grammar check said it was wrong. But I always thought that the rule was: an = when a word starts with a,e,i,o,u. But then I figured, yeah it does sound strange.
Buchanan was nominated by the Democratic Party in the 1856 presidential election. Throughout most of Pierce's term, he had been stationed in London as a minister to the Court of St. James's, so was not caught up in the crossfire of sectional politics that dominated the country.
John C. Breckinridge, 1860 Presidential candidate nominated by the Southern Democrats, was Vice-president under James Buchanan. This just-the facts biography from the U.S. Senate gives details of his political career.