As Mr Clinton has risen, so the Republican from Georgia has fallen, confirmed by the polls since the end of last year as the most unpopular American politician of his era. This week Mr Gingrich's political annihilation could be complete. He faces, as Lady Thatcher once did, a vote of confidence from his own party, the outcome of which will decide whether he remains Speaker of the House, or whether he is condemned to what for him would be the oblivion of the congressional back benches.
When the House reconvenes on Tuesday morning for the first time since the 5 November elections, high on the order of play will be the election of the Speaker. All 435 representatives cast a vote: 227 Republicans, 207 Democrats and one independent. The winner is chosen by simple majority, so ordinarily the outcome would not be in doubt. It certainly was not two years ago this week, when Mr Gingrich was not so much elected as crowned, acclaimed - in a term he himself coined - as "the leader of the Second American Revolution".
But recently, as his detractors have long suspected, the House ethics sub-committee was presented with irrefutable evidence that he had violated congressional rules by using a tax-exempt foundation he set up to finance his election campaigns . Most of the Republicans in Congress, notably the leadership, are behind him. But at the latest count 27 of his party colleagues were refusing to commit themselves to his re-election. Twenty defections on Tuesday would cost him his job.
Mr Gingrich himself is keeping out of the public spotlight but he has been speaking on the phone to every Republican member of the House. Other Republican leaders have been doing the same, in a frenzy to whip their colleagues into line. Haley Barbour, the party chairman, displayed the measure of his alarm by writing an article in Friday's New York Times explicitly savaging the Democrats for their attacks on Mr Gingrich, implicitly imploring Republicans to stand by their man.
It is with some bafflement that the Speaker must be contemplating how things ever reached this pass. Today he is fighting for his political life when it seems like only yesterday that he was fighting to transform not only America but, as he would say, the entire human race.
"I have an enormous personal ambition," he declared when he was at the apex of his career. "I want to shift the entire planet and I'm doing it ... What is ultimately at stake in our current environment is literally the future of American civilisation." He was the man whose legacy would be eternal, the crusader who would slay the infidel Democrats. "I am a genuine revolutionary; they [the Democrats] are the genuine reactionaries. We are going to change the world; they will do anything to stop us."
In that last regard he was right. Mr Clinton stemmed the Republican tide by quite shamelessly making the Republican agenda his own, rhetorically hijacking the two pillars of Mr Gingrich's revolution, balancing the budget and welfare reform. On welfare reform the president went beyond rhetoric and actually signed a bill that put an end to 50 years of guaranteed government hand-outs to the poor.
Mr Clinton's genius was that he came up smelling of roses, while Mr Gingrich was left wearing the label of Scrooge. For those Republicans hesitant about reconfirming Mr Gingrich as Speaker a factor that will weigh heavily, quite apart from his ethical improprieties, is the perception that his unpopularity makes him a liability .
Not only does the public view him as mean, they also judge him to be just a little too wacky - a little too much like Ross Perot - to occupy the third highest office in the land. His earnest public musings about the similarities between politicians and chimpanzees, his fascination with dinosaurs and boa constrictors and Kalahari bushmen who hunt giraffes, his fantasies about weightless sex in space: all have provided fodder for a thousand talk-show jokes.
Those Republicans who are pondering whether to stick the knife into their erstwhile Caesar must also be weighing the cost to their party if they flinch. Were Mr Gingrich's fate to be decided by a national vote, the outcome would not be in doubt.