Ariel Sharon, the leading right-wing rival to Prime Minister Shamir, then issued a challenge to Mr. Shamir's leadership.

Prime Minister Ehud Barak of Israel unexpectedly announced his resignation tonight, pushing forward new elections to early February and seizing the political initiative from his right-wing rivals.

Mr. Barak faces new elections next spring, and the polls show him trailing his potential right-wing rivals.

Also on Sunday, Prime Minister Sharon gained qualified backing from his top right-wing rival, Benjamin Netanyahu, for Mr. Sharon's plan for a Gaza withdrawal.

He was defeated in a 1961 election by a right-wing rival, Sir Eric Gairy, but returned to office 18 months later when Sir Eric was forced to resign.

What made the attack on Le Sillon, which was doctrinally quite orthodox, more reprehensible was that an extraordinary tolerance was shown to its extreme right-wing rival, Action Francaise.

Their main right-wing rival was another former Communist Party venue, România Liberă, which openly reproached on the FSN that it was monopolizing power, and which identified itself with liberalism and pluralism.

Mr. Clark, an Albertan who briefly served as prime minister two decades ago, announced the run one week after a similar election bid was announced by his right-wing rival, Stockwell Day, the new leader of the Canadian Alliance.

The mullahs made common cause with Franz Josef Strauss, Prime Minister of Bavaria and right-wing rival of Chancellor Helmut Kohl.

It is just the sort of careful balancing act Mr. Shamir has mastered in the years he has been caught between right-wing political rivals in his own party and left-wing coalition partners - all of whom have the power to bring down the Government.