LONDON -- Neil Kinnock lost his temper in the House of Commons not too long ago and called a Conservative member of Parliament "a jerk."
A blizzard of press criticism fell on him.
It was a mistake. More in anger with himself than regret, he apologized.
Mr. Kinnock is a politically impassioned man who has spent the last half-decade shedding his color and suppressing his passion. The Neil Kinnock of the early days was too rich for Britain's mainstream electorate.
But sometimes the passion will come out. About three years ago, during a television interview on the subject of the Conservatives' handling of the economy, he burst forth: "Look, they are smashing up our country. I'm serious about that. I don't give a sod about the politics of it. They are smashing up the country. They should be on the rack."
The next day the papers screamed of his "temperamental failing."
To win Thursday's general election and put the Labor Party back in power after 13 years, Mr. Kinnock believes he must convey the impression that he is a man of restraint.
Thus, appearances are all important, for it is on appearances that the Conservatives are trying to defeat him. They portray him as an irresponsible socialist who would tax Britain into the poor house, dismantle the country's defenses and surrender its sovereignty to Europe.
Mr. Kinnock is not a centrist. His program, which concentrates on rehabilitating the apparatus of the welfare state, is socialist. But the fiscal policies he offers, the refusal to borrow to finance improvements in the welfare system, for instance, have won him some grudging respect among bankers and financiers.
Mr. Kinnock went to the House of Commons in 1970. He was elected Labor Party chief after the Conservative rout of Labor in the 1983 elections.
Even before he took over, Mr. Kinnock rethought his own politics, which were decidedly to the left. Once in charge and seized by the realization that it was all up to him, he purged the extremist left, moved the party toward the center and has worked to win back the confidence of the electorate lost during the '70s and early '80s.
Most people who know or have observed Mr. Kinnock do not regard him as a man with a towering intellect, nor is his academic record distinguished.
But Brian Barry, a specialist in social legislation, says, "That may not be a prerequisite for a prime minister. Kinnock [as prime minister], I suspect, would have something in common with [Clement] Atlee, who was a very successful Labor prime minister. Atlee said the thing is to be a good butcher. Kinnock has the ruthlessness to ax people who are not doing well."