The great theme of the end-of-year political assessments in the United States is that Bill Clinton is a lame-duck president. Not only are the Republicans widely expected to beat him in 1996, but such is the dismay of Democrats at the thought of running with Clinton at the top of the ticket that they may well decide to run another candidate.


The game is not up yet. It is worth noting that Clinton's latest opinion poll ratings, of 50 percent disapproval and 42 percent approval, were almost exactly the same as those of Ronald Reagan after his first mid-term elections in 1982. And Reagan went on to be re-elected in 1984.


There are two differences. One is that Reagan in 1982 had yet to deliver his economic recovery; Clinton has squandered his. The other difference is that Reagan always maintained a devoted core of ideological support. Clinton has squandered this too. The Democratic left never trusted him, and moderates no longer see him as one of them.


But it remains a very difficult business, getting rid of an incumbent president who wants to run again, as Clinton does. The last three times it happened, when Pat Buchanan ran against George Bush in 1992, when Senator Edward Kennedy ran against Jimmy Carter in 1980, and when Ronald Reagan ran against Gerry Ford in 1976, the challengers all lost. Worse still, they so weakened their own party with the internal battle that the incumbent lost the subsequent election.


And bear in mind that Ted Kennedy in 1980 and Ronald Reagan in 1976 were imposing political figures. There is no such figure yet lifting any comparable high profile above the Democratic parapet this time around.


The usual suspects, who include Senators Bob Kerrey, Sam Nunn and Bill Bradley, are giants inside the Washington beltway, but of much less prominence among the electorate. The only figure who would fill the stature gap to have a real chance of toppling Clinton at this stage would be Vice President Al Gore, who is thought far too upright and loyal to do it.


But much of 1995 will be taken up with speculation about this, because if there is to be a challenge from Clinton's own party, it will have to come fast.


That familiar era of leisurely primary elections, from New Hampshire in February to California in June of the election year, is over. For 1996, the big states have all shifted their primary dates forward to the month of March.


This flurry of winter-spring primaries means that any credible challenger, Republican or Democrat, will have to assemble a massive bankroll by December of this year to pay for television ads in some of the most expensive media markets in the country. That in turn means appointing a full-time fund-raising team over the next four months. And any Democrat who takes the risk will proffer a still-potent incumbent president a target to attack.


In short, the balance of probabilities is that Bill Clinton will be his party's candidate in 1996, and that he is by no means fated to face a Democratic challenge in the primaries -- except perhaps for a quixotic campaign from the left by the perennial hopeful Jesse Jackson.


Don't write off Bill Clinton yet. At this mid-point of his presidency, after the bruising political defeat of the congressional elections, he is at his lowest ebb. He remains a formidable campaigner, with the resources of the presidency behind him, and no credible Democratic challenger yet in sight.