Karl Rove equates Birtherism with... people who thought the 2000 election recount was handled unfairly:

SPIEGEL: It is, however, difficult to understand the smear campaigns against Obama, claiming that he falsified his birth certificate and is not the legitimate president.
Rove: Please, with all due respect. That's what happened for eight years with Bush. Just before George W. Bush was sworn into office, on "Meet the Press," Dick Gephardt, the Democratic leader of the House of Representatives, was asked by Tim Russert twice if he believed George W. Bush was the legitimately elected president of the United States. And twice, the leader of the Democrats refused to answer the question. I was shocked, and that was what we had to deal with for eight years.”

Actually, they didn't have to deal with it for eight years. Those elected officials harboring reservations about Bush's legitimacy were hounded with hostile questions by the national media until they clammed up, and the issue disappeared entirely after 9/11, which pundits bizarrely but unanimously declared had ended all questions about Bush's legitimacy.

Bush was elected due to poorly-designed ballots and malfunctioning ballot equipment located disproportionately in Democratic districts, combined with resolute efforts by Bush's campaign, Republican elected officials and five Republican-appointed Supreme Court justices to prevent any recount that might partially correct those ballot-counting malfunctions. That much is simple fact. Whether this casts doubt upon Bush's electoral legitimacy is a matter of opinion. In any case, it's not remotely equivalent to the factual inaccuracy underlying the Birtherism of the right.