Lieberman may be right of center in the Democratic Party, but he is left of center overall, compared to the public at large. Does the author really think that having a second hard-left candidate on the ticket in 2000 would have gained more votes than the ticket would have lost?
One important difference between 1968 and 2008 is that Nixon didn't have to worry about Hillary.
Hillary needs support with election critical Global warming Science.
Who's better able to lend support than Al Gore, who's expertise besides Global Warming is a claim of fame by having invented the Internet.