I think every single registered Democrat in America should get a tattoo that reads "SENATORS DO NOT WIN PRESIDENTIAL ELECTIONS", get it tattooed across their forehead backwards so they can read it everytime they get up in the morning and look in the mirror.
Now, for all you children aspiring political junkies, why do you think this is? Do you think it's merely an amazing coincidence?
In a hypothetical race Rudy versus Hillary, Rudy wins,
In a hypothetical race with Mitt Romney versus Hilary Clinton, Romney wins.
End of story.
however there is a first time for everything. of course, senators aren't going to be president until the first senator becomes one.