If there was a "liberal" version of Dubya, I doubt he'd get as far as the White House. Dubya's right-wing enablers would have seen to that.
If there was a "liberal" version of Dubya, the right-wing slime machine would have been all over him and his business dealings and, unlike What's-his-name and Harken, and What's-his-name and Arbusto, would have been screaming for his criminal investigation and indictment before he even reached the end of the primaries.
If there was a "liberal" version of Dubya, the corporate media, sluggards all when it comes to investigating well-connected Republicans, would have been investigating his previous record as a state official. They wouldn't have had to dig very far to find something.
If there was a "liberal" version of Dubya, the center as well as the Far Right would have been mocking him as an inarticulate boob who mangled the English language and as someone unable to think clearly or logically.
A "liberal" version of Dubya, even if he got as far as the nomination for the Democratic Party of the United States, would probably have been chewed up and spat out by the Republican presidential nominee in the general election--unless the Republicans nominated a near-duplicate to the fellow currently at 1600 Pennsylvania Avenue.
Face it, kiddies, I doubt that there will ever a "liberal" version of Dubya. In these times, Democrats are forced to find better Presidential candidates than the ones the GOP are likely to try to foist on the American voter.