Sharon made the request on Monday, just hours after he decided to leave the Likud party he helped found in 1973, and to compete in the next election as the leader of a new party.
Earlier in the day, Israel Radio and one of Sharon's top advisers said he had decided to quit Likud and form a new movement.
Asked if the prime minister had taken the decision, adviser Asaf Shariv confirmed on Monday: "Yes. He will announce it sometime today."
Israel Radio had said Sharon, after marathon talks with aides and associates, decided to break with the party and run separately in the next national elections, likely to be moved up from November 2006 to March.
The dramatic announcement comes after the Labour party announced it would quit the ruling coalition.
Sharon has already begun contacting political allies to join a new party which he plans to head, the radio said.
The 77-year-old former general had been expected to announce his decision at a meeting on Monday with members of the Likud parliament faction.
Leader Amir Peretz is charting a
new course for leftwing Labour
Confidants say Sharon wants to seize the chance that polls say he has to defeat the left-of-centre Labour party in a snap election.
He would then pursue plans to end conflict with the Palestinians without having to battle Likud hardliners who oppose giving up West Bank land.
Earlier on Sunday, the central committee of the leftist Labour party, encouraged by new leader Amir Peretz, voted overwhelmingly to leave the government.
The party had originally joined the coalition to help Sharon counter rightist Likud rebels who opposed his withdrawal from the occupied Gaza Strip.
"Let the revolution begin," said party official Eitan Cabel as he announced the result of the vote in a show of hands.
Sunday's events were the expected first step in a week that will reshape Israeli politics, thrown into turmoil since union leader Peretz defeated veteran peacemaker Shimon Peres in a surprise Labour leadership vote.
Several commentators had predicted Sharon would quit.
"He is liable to set in motion a political migration on a scale that the Israeli political map hasn't witnessed since the state of Israel was founded," wrote Shimon Shiffer in the best-selling Yedioth Ahronoth daily.