If failed presidential candidate Bob Dole gets tired of the old man's jokes, just imagine what life is like for 94-year-old Senator Strom Thurmond. Democratic Senator Tom Harkin even brought Mr Thurmond into the firing line when making fun of House Speaker Newt Gingrich's US$300,000 loan from Mr Dole to pay off his fine for violating House ethics. The loan was not such a big deal, Mr Harkin said, because after all, Mr Thurmond 'helped pay Abe Lincoln's way through law school'. Even if the joke was stretching the South Carolinan senator's age just a little, the man born in 1902 is hardly fazed by being the butt of so much humour. Indeed, when a man can marry a second wife 44 years his junior and then father the first of four children with her at the age of 68, it is not hard to see who is having the last laugh. Whenever the oldest surviving member of Congress attends political functions in Washington, his date would be the envy of men 60 years younger. The woman - a 20-something glamorous blonde with a southern accent to melt the heart - is, however, his daughter. Age has its advantages in other areas too. As the oldest surviving member of the Senate, Mr Thurmond is third in line to the presidency after Vice-President Al Gore and Mr Gingrich. While that prospect, no matter how much a long shot, may cause concern, Mr Thurmond's longevity was a cause for celebration last week, when he became the longest-serving United States senator in history. Tracing those 41 years and 10 months of the senator's life is in itself a mini-history of post-war politics. Going back all the way to the 1930s, when his political career began, and one is well on the way to seeing America's 20th century encapsulated in one life. The genteel but sometimes feisty southerner has recently earned the title of the 'Energizer Bunny', because he keeps going and going while politicians all around him run out of batteries. He is fond of boasting that he works out every day, but it is more his political energy and flexibility which appears to have been the fountain of youth. The twists and turns he has taken in his long career not only demonstrate the sometimes Machiavellian nature of Washington life, but also mirror the changes that have affected politics in the nation as a whole. Having started in politics in South Carolina before the war as a Democrat, Mr Thurmond came back from active service in Europe and successfully won the governorship of his state. But in 1948, disaffected with Democratic politics, he made a famous third-party stand for president. Facing off against incumbent Harry Truman, he stood on a platform of states' rights against Washington interference and even managed to snatch a few of the loyal southern states. He returned to the Democratic Party fold and did get to Washington in 1954 - as a senator - and has stayed ever since. But his maverick behaviour at that time can only be understood in the context of what it was like to be a Southern Democrat during that era. Mr Thurmond hit Washington at a time when the entire region was under a Democratic stranglehold - largely as a hangover from the civil war, when southerners fought (and lost) against the Republicans and Abraham Lincoln. Longstanding prejudices made it impossible for most Republicans, even those who were not Yankees, to get elected in the south. This gave rise to the 'Dixiecrats' such as Mr Thurmond - Democrats who were far more conservative than most of their Republican or Democratic peers, then or now. If there was one issue which united the Dixiecrats in the 50s, it was race. Like so many of his counterparts, Mr Thurmond fought to maintain segregation and opposed the growing tide towards civil rights. Perhaps the most ignominious feat of his career was the 24 hours and 18 minutes he stood in a Senate chamber, staying on his feet to filibuster one of the first Civil Rights bills in 1958. It remains the longest individual filibuster in Senate history. When the senator abandoned the Democrats for the Republicans in 1964, his irritation at the liberal Kennedy administration's agenda was also on his mind. Given that kind of record, it would seem amazing that Mr Thurmond gets any black support at all. But at the last election, he managed to pick up around 25 per cent of South Carolina's African-American vote. That feat says much for the way he was able to realign himself to recognise the growing black population in his state. Whether through cynicism or pragmatism, Mr Thurmond was the first southern senator to employ black aides. Such has his mastery of local politics been, that virtually no Democrat nor Republican has dared challenge him seriously for 40 years. But even though he will be 100 before his Senate term expires, Mr Thurmond shows no sign of wanting to be put out to grass. Whatever one thinks of him, he is the most enduring monument on Washington's sweeping mall.