Mr Gore had been billed as the guest presenter, and trailers had been broadcast throughout the day advertising his appearance, along with the star guest, Oprah Winfrey. The programme was to be devoted to the school shootings at Littleton in Colorado, which have prompted a frenzy of soul- searching across the United States.
Mr Gore, who represented the Administration at the Littleton memorial service last weekend, was also to have reported on his tour of the tornado damage in Oklahoma and Kansas earlier in the day.
By mid-afternoon, however, the Vice-President's proposed transformation into talkshow host had generated a storm of its own. The Republican national chairman, Jim Nicholson, wrote to Larry King saying that Mr Gore's planned appearance raised "serious concerns". He said he doubted Mr King would feel "comfortable if your fine programme is turned into a contribution of free air-time to the Gore for President campaign".
The Republican Party called on its members to e-mail their protests to CNN and to use the phone-in segment of the programme to voice their objections. One of CNN's staff correspondents accredited to the White House broke ranks with his employer, saying that the invitation to Al Gore raised questions about the network's objectivity: "If we are going to give him an hour, how can we defend not giving every other candidate the same opportunity?" And in a country where all air-time is paid for, CNN might also have been subject to legal challenges from other presidential candidates claiming that the broadcast was an "in-kind" contribution to the Gore campaign.
The programme could have given Mr Gore, whose awkwardness before the camera is becoming a serious political liability, a chance to loosen up as interviewer rather than interviewee, helped out by the doyenne of talkshow hosts, Oprah Winfrey, not to mention a guaranteed audience of millions.
In the event, however, viewers switched on to see Larry King in his customary place, and hear him read a very unaccustomed explanation for the switch.
The programme, he said, had made the decision "after taking a long, hard look at the political calendar" - that is, the fact that the presidential race is hotting up - and "the Vice-President graciously agreed to give me back my microphone". Mr Gore then spoke, with no more fluency than usual, about his tour of the tornado damage - initially naming the wrong state as the one with greatest damage. Ms Winfrey did not appear.
The debacle was the latest instance of the jinx that attaches to Mr Gore in his relations with the media - a jinx that seems to be considerably assisted by poor advice and political insensitivity.