AC

When choosing a running mate, Mitt Romney will consider many factors: Can this person offer a bump in the polls? Will he or she excite the base? Could this person take the reins if necessary? Will we get along? He will also weigh the candidates' ideological moorings. Let's take a look at where the candidates stand based on their voting records in public office. For the answer, we dive into the informative--albeit imperfect--world of congressional scorecards. Advocacy groups and news outlets commonly rate lawmakers based on some standard relevant to the organization, which helps us determine where each contender falls on the ideological spectrum. In the Senate, Rob Portman of Ohio, Marco Rubio of Florida, Kelly Ayotte of New Hampshire and John Thune of South Dakota commonly appear on lists of possible running mates. Scorecards that measured voting records in 2011 suggest that among these, Rubio had the most conservative voting record, and Portman the most moderate. Ayotte and...