By the numbers:
Mitt Romney has won more than 3 million votes, Rick Santorum fewer than 2 million.
Santorum has won a single state, Tennessee, with a city among the 20 largest in the United States.
Of the critical states that President Obama won in 2008 that the GOP hopes to win back this time, Romney has won five of them (New Hampshire, Florida, Nevada, Ohio, Virginia), and Santorum has won one (Colorado).
In Ohio, Santorum lost the women's vote by three points, much more than the margin of difference between him and Romney.
Sen. John McCain (R-Ariz.) lost 19 states on the way to the nomination; Romney has lost eight.