My understanding is that, whilst Breckinridge is often portrayed as the ‘southern’ Democratic candidate in the election (as opposed to Douglas, the ‘northern’ Democrat), the reality was that he was more the candidate of the Buchanan faction of the party.
I would argue the opposite; Breckinridge was the Southern candidate who was also supported by Northern Buchananites. Buchanan despised Douglas (largely because of disagreements over Buchanan's handling of KS) and did indeed throw his support behind his VP, but Buchanan had relatively little to do with Breckinridge's nomination, which was the work of dissatisfied Southerners.
