"They are the most essential, shall I say, the most crucial elections in the history of the state of Israel," Peres told reporters 48 hours before Israelis vote.
"I think it will be terrible if the peace process will be interrupted or stopped and we shall go backwards. It will be extremely difficult later on to correct it," the Labour party leader said.
But polls conducted just before Sunday's sole debate between the candidates included one showing Peres's lead shrinking to a precarious 2.4 percent. In addition, most Israeli commentators said Netanyahu had emerged victorious from the debate.
Ahmed Tibi, an aide to Palestinian President Yasser Arafat, said he feared the Labour leader was headed for defeat because he had alienated the traditional support of Israeli Arabs through last month's "Operation Grapes of Wrath" in Lebanon, where more than 200 civilians were killed.
The debate shown on Israeli television offered contrasting views of peace and security. Netanyahu pounded away at his campaign theme that Peres's efforts to make peace had increased the danger for Israelis.
Peres, successor to Yitzhak Rabin who was assassinated by a Jewish opponent of his peace policies last November 4, has promised to pursue peace with Arabs even if it means withdrawal from captured territory.
Netanyahu has emphasized security over peace talks, focusing on Israeli insecurity caused by Moslem suicide bombings in late February and early March that killed 59 people.
He vowed to step up settlement on occupied land and ruled out self-determination for Palestinians or return of the occupied Golan Heights for peace with Syria.
A poll of 1,031 voters in the newspaper Yedioth Ahronoth conducted just before the debate showed Peres had 49.5 percent and Netanyahu 47.1 percent, down from 51 percent for Peres and 45 percent for the Likud leader before.
Those not expressing a favorite fell from 4 percent to 3.4 percent. The poll had a margin of error of 3 percent, leaving the outcome of the Wednesday vote too close to call.
A second poll of 583 voters put Peres four percentage points ahead, down from 4.5 in the previous sample. A 4 percent margin of error again left the outcome up in the air.
In another boost to the Likud leader, a prominent Israeli rabbi who could deliver crucial votes expressed support for Netanyahu.
With the hours to the vote ticking away -- and no more advertising allowed after Monday -- the 46-year-old Netanyahu had a full day of campaigning.
In contrast Peres, 72, spent most of the day in his Jerusalem office, emphasizing his position as prime minister -- an image of experienced "safe hands" that he has sought to portray throughout the campaign.
For the first time, Israelis will cast two ballots: one for prime minister and a second for a party. The man elected prime minister could head a party the electorate does not want in power, increasing small parties' bargaining leverage in building a coalition.
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