It came to me in a flash.
The Democratic voters of Connecticut have stated that Joe Lieberman is not a Democrat. Harry Reid has said that, for the purposes of the Senate, Lieberman is.
Since Senator Reid has demonstrated that he can change party affiliation by fiat, why not just declare that all Senate Republicans are now Democrats and Voila! A 100-seat, filibuster-proof, rubber stamp majority!
Alternatively, if Franken and Martin do not win their elections, just declare that Mitch McConnell and Orrin Hatch are now Democrats, and there's your sixty seats.