Foreign Minister Silvan Shalom, speaking on Wednesday to Israel Radio from a conference in Tunisia, said Sharon told him at a recent meeting there was "no reason to delay the matter" of an early national election, now due in November 2006.
Amir Peretz, a trade union leader who ousted Shimon Peres as Labour's leader in a 9 November party ballot, has vowed to quit Sharon's coalition, saying he will seek the prime minister's agreement on an election date in talks on Thursday.
"I met the prime minister after the cabinet meeting on Sunday and we discussed it (elections), and if Peretz wants elections he can get elections," Shalom said. "March is the right month."
Peretz, 53, a Moroccan-born immigrant, made his pledge to withdraw from Sharon's government a centrepiece of his campaign to replace Peres, 82, accusing the government of hurting Israel's poor with its free-market reforms.
Peretz, who shares Peres' dovish views on Israel's conflict with the Palestinians, has said he will push for elections in March or May.
The exit of centre-left Labour from the coalition, which it joined to help Sharon carry out a Gaza pullout in September, would strip it of its parliamentary majority.
Sharon met Likud lawmakers to discuss what he called the "possibility of early elections". Aides say he wants to buy time, hoping Peretz's boost from his surprise victory will fade.
But Sharon sees little chance of serving out his term when he also faces pressure from rebellious members of his own rightist Likud trying to punish him for the Gaza withdrawal.
Shimon Peres lost his position as
Labour chief to a dovish leftist
If Sharon and Peretz fail to agree on an election date, Labour would likely vote in favour of a preliminary motion due to be presented by rightist opposition parties on Monday to dissolve parliament and hold a national ballot.
Labour, which led the creation of the Jewish state in 1948 and later became the standard-bearer for peacemaking, is now weaker than ever after voters hardened by a Palestinian uprising abandoned it in favour of Sharon's tough military approach.
Recent opinion polls showed Peretz's toppling of Peres had given Labour a slight lift but not enough to unseat Sharon.