Here is a brilliant analysis of the primary results from April 23rd compared to McCain's in 2008 at essentially the same stage of the race. This is from a gentleman "Frank" who is commenting at Conservatives4Palin and who makes an outstanding comparison.
Two of the races drew interest from me. Rhode Island and Pennsylvania were held in 2008 after McCain had essentially won the nomination just as Romney has now.
2008 Rhode island McCain 17,480 Huckabee 5,847 Paul 1,777 Uncommitted 570 Total Votes 25,674
2012 Rhode Island Romney 9,157 Paul 3,462 Gingrich 878 Other 579 Total Votes 14,489
Romney only got a little over 50% of what McCain got and McCain was not Mr Charisma. The turnout was down over 11,000.
2008 Pennsylvania McCain 595,175 Paul 129,323 Huckabee 92,430 Total Votes 816,928
2012 Pensylvania (99%) Romney 462,123 Santorum 146,337 Paul 104,942 Gingrich 83,523 Total votes 786,925
In Pennsylvania, it looks like turnout may be slightly below or even with the 2008 race. However Romney is running over 100,000 votes behind Mr Charisma, John McCain.
Overall, people are not rushing out to support Mitt Romney. When you are trailing John McCain, that is not good news. The percentages were not that impressive. Not a good night for Romney.