I vaguely recall that it was supposed to portray some blue collar, working class person.

I just randomly found this quote, it seems interesting:

If you visit the cartoon's elaborate Web site -- do pluggers have elaborate Web sites? -- you learn that "Pluggers" was not created by some working class hack, but by nothing less than a committee. Reading the site's voluminous background information, you learn that "Pluggers" was conceived in 1993 by a group of five middle-aged men, none of whom seems to have much in common with the proletariat they seek to depict. One is a successful entrepreneur. One is a TV sitcom writer. Another is the "former CEO of a major American company." MacNelly, who prepped at Phillips Academy, is the well-off, Pulitzer Prize-winning editorial cartoonist for the Chicago Tribune, who lives in the "rolling hills" of Virginia and collects antique cars. These people are Pluggers?

https://web.archive.org/web/20100721065413/http://www.salon.com/media/media960710.html

So I guess it's the whole right wing portrayal of working class people, as opposed to those city people??