Let's say Oakvale and I are the two main candidates running for the Democratic nomination. Oakvale runs a quasi-libertarian, socially liberal campaign that calls for relatively moderate economic positions while I run a more economically-focused campaign with a social platform that's slightly right of center. Using the 2012 R primaries as a guide (why not?):
I (green) jump out to an early lead on more rural states while Oakvale (red) does better in suburban states. He runs slightly better, though it's close, in the west.
However, Oakvale builds up some momentum going into Super Tuesday thanks to social liberals. Other candidates drop out after MO/CO/MN.
I strike back by winning the South on Super Tuesday, but Oakvale carries on. I keep winning in the South, but the large delegate prizes are still in play.
Oakvale wins a crucial showdown in Illinois, and follows it up with a win in Wisconsin and Maryland. When the northeastern primaries roll around, I manage to win PA, but nothing else.
My campaign fumbles in North Carolina on the strength of the Research Triangle, overriding victories in Indiana and West Virginia. Again I'm dealt a surprise defeat in Nebraska. I narrowly hold on to Texas, but Oakvale decisively sweeps the first contests of June to claim a bare delegate majority on the final day (with a final push by superdelegates aiding him in the process).