Sharon is expected on Monday to give parliament a defence of his controversial disengagement plan which he has said will lead to the "relocation" of some settlements in the West Bank and Gaza Strip.
But opposition Labor party leader Shimon Peres said on Monday the weakness of Sharon's cabinet and the presence of four ministers among Sunday's protesters meant the prime minister was unlikely to act.
Though police estimated up to 120,000 people were at Sunday's Tel Aviv rally, many appeared to be teenagers, too young to vote.
"The uprooting of settlements tears the nation," read one protester's sign. "Sharon, resign - we don't want you any more," read another.
Sharon said last month he would uproot some settlements and impose a boundary on the Palestinians if no peace deal is reached in the next few months.
And last week he told activists from his Likud Party that under any peace deal, some settlements would have to be moved.
But the make-up of his cabinet means Sharon's talk of uprooting settlements is unlikely to be translated into action, opposition leader Peres said on Monday.
The presence of four cabinet members at a mass pro-settlements rally on Sunday night indicated that the premier was unlikely to want to rock the boat and risk the break-up of his coalition government, said Peres.
"The fact that the National Religious Party (NRP) and the National Union Party (NUP) are members means that Sharon's government is condemned to stick to the status quo and cannot proceed with unilateral withdrawals or the dismantling of settlements," Peres, former prime minister, told public radio.
Some 20 MPs from Sharon's own Likud party were among the 100,000 strong crowd at the rally in Tel Aviv. Minister without portfolio Uzi Landau, a Likud member, was also present alongside cabinet ministers from the untra-right NRP and NUP.