JERUSALEM (AFP) - Israel's incoming cabinet, which is in the final stages of being formed, will count just 20 ministers down from 28 in what the press on Tuesday hailed as a major coup for the centrist Yesh Atid.

The more streamlined cabinet had been a central plank of the campaign of Yesh Atid leader Yair Lapid, whose newly-formed party won a shock victory in the January election, becoming overnight Israel's second political faction.

The news emerged late on Monday as Prime Minister Benjamin Netanyahu tried to iron out the final details of a long-awaited coalition agreement which will set in place a new government just days before a top-level visit on March 20 by US President Barack Obama.

Still to be resolved is the key issue of who will receive the education portfolio, which has until now been held by Netanyahu's rightwing Likud and which he wants to keep, but Lapid is also pushing for the post to be given to his deputy, Rabbi Shai Piron.

The two parties are also haggling over which of them will take the interior ministry, which until now has been held by the ultra-Orthodox Shas party that is not part of the incoming government.

Netanyahu's agreement to have just 20 ministers serving under him was on Tuesday hailed as a second significant victory for Lapid, who last week managed to make good on another of his electoral promises - a coalition without the ultra-Orthodox.

It is "a major accomplishment for Yair Lapid's Yesh Atid party, which has demanded a leaner, more streamlined cabinet," wrote Haaretz's Jonathan Lis.

The agreement meant there would be no ministers without portfolio in the next cabinet for the first time since 1951, he wrote, saying the move, which came at the insistence of Yesh Atid, "is expected to save taxpayers millions of shekels."

"Each minister without portfolio position costs the tax payer around two million shekels (S$678,000) a year," he wrote, saying the figure was sometimes as high as five million shekels.

"Last year, the total cost to the treasury of ministers without portfolio and ministers with special responsibilities who operated within the prime minister's office came to about 100 million shekels," Lis said.

Netanyahu is in the final stretch of a six-week period he was granted in order to piece together a coalition of MPs with a majority of at least 61 in the 120-seat Knesset.

Should he fail to ink a deal by Saturday night, the task will be handed by President Shimon Peres to another party leader.

Obama is set to arrive on March 20 for a three-day visit - his first since being elected president in 2008.