WARSAW, DEC. 12 -- Lech Walesa resigned as Solidarity chairman today and asked the labor union he led for a decade to support the "big changes" he intends to make as Poland's president.

Walesa, who is to be sworn in for a five-year presidential term about Dec. 21, is conducting "intensive talks" about naming a new prime minister and cabinet, said Solidarity spokesman Andrzej Drzycinski.

The president-elect urged Solidarity to be active in free parliamentary elections next spring and help Poland weather the difficult transition to a capitalist economy and democracy. He appealed for support in fending off any "attack of the Tyminskis," referring to Stanislaw Tyminski, his defeated opponent in Sunday's runoff election who had promised quick prosperity for economically struggling Poland.

Tyminski left for Canada today after posting a $100,000 bond to assure his return to answer charges that he slandered Prime Minister Tadeusz Mazowiecki in the campaign.

Meanwhile, outgoing President Wojciech Jaruzelski delivered his farewell to the nation in a televised speech Tuesday night.

Jaruzelski apologized for "each harm, pain and injustice" caused during his nine years in power -- apparently referring to his 1981 decision to impose martial law in an effort to crush Solidarity and the ensuing repressions and stalemate.

"The word 'sorry' may sound all too casual," Jaruzelski said. "But I cannot find another one."