Unfortunately, I can't distribute the raw data for this, but you can obtain it from CQ Press and ICPSR if you have access to those sites.
Put the extract the data to ./data
and run Rscript bellwether.R
Code for my article "There Are No Bellwether Counties" http://www.huffingtonpost.com/adam-obeng/there-are-no-bellwether-c_b_9777628.html
R