Israeli Prime Minister Benjamin Netanyahu was to formally unveil his long-awaited coalition government on Thursday that will be sworn in just days before a visit by US President Barack Obama.
After nearly 40 days of intensive negotiations with potential partners, Netanyahu was expected to announce a deal between his Likud-Beitenu alliance, the centrist Yesh Atid and the far-right Jewish Home.
He has already signed an agreement with the small centrist HaTnuah party.
Party heads had been expected to ink the coalition contract at around midday but negotiators told public radio there had been a delay for last-minute fine-tuning.
"We are busy with the final details of the coalition agreements," Netanyahu told senior members of Likud-Beitenu in comments broadcast at around 1200 GMT.
In a posting on his Facebook page, Yesh Atid leader Yair Lapid said the signing of the deal was "likely to be tonight."
"Barring any last-minute hitches, it should be signed today," said Ashley Perry, spokesman for the hardline Yisrael Beitenu which ran on a joint electoral list with Netanyahu's rightwing Likud.
The Israeli leader said he expects the new government to be sworn in a ceremony likely to take place on Monday, just two days before Obama arrives for his first visit to the Jewish state since becoming president.
He had been under huge pressure to present a lineup with a working majority of at least 61 MPs within the 120-seat Knesset (parliament) before a March 16 deadline.
"There is a government," Likud spokeswoman Noga Katz told AFP, saying details of the lineup would be released "in due course."
Haaretz newspaper said Netanyahu would formally notify President Shimon Peres about his new government.
Media reports said the agreement would see Netanyahu heading a coalition with a majority of 68 comprising Likud-Beitenu (31), Yesh Atid (19), Naftali Bennett's Jewish Home party (12) and HaTnuah (6) headed by former foreign minister Tzipi Livni.
The deal is expected to see Netanyahu presiding over a slimline cabinet of 21 ministers, down from 28 in the previous administration.
The 11th-hour deal was widely seen as a victory for political newcomer Lapid, who wrested the influential education portfolio for his party's number two and who will himself become finance minister.
Although Likud-Beitenu is expected to have a majority in cabinet, Netanyahu's authority will be less than it was in the outgoing government, which included the more malleable ultra-Orthodox parties, who are absent from the new lineup for the the first time since 1984.
"The clash of the Titans over the education portfolio ended with a victory for Lapid," wrote Haaretz's political commentator Yossi Verter.
"It was yet another victory, after he had forced Netanyahu to part from his ultra-Orthodox partners and imposed a painful reduction in the number of government ministers."
Netanyahu played up the importance of Likud's retained portfolios, including defence and foreign affairs.
"These are the most important portfolios for the administration of the state," he said, highlighting Likud-Beitenu's cabinet majority.
"We worked together to achieve a clear majority in the cabinet (for Likud-Beitenu) so that we can ensure the policy in which we believe," he added.
-- 'Story about Lapid's victory' --
During the negotiations, Lapid pushed for a coalition without the ultra-Orthodox, a reduction in the cabinet size and for his party to take the prestigious education portfolio -- all of which he got.
"The story here is a story about Lapid's victory. He didn't appear desperate because he wasn't," wrote Maariv's Shalom Yerushalmi, saying Netanyahu had understood the message and been forced to play ball.
Commentators said the new government would have a clear rightwards bent, with hardliners set to assume responsibility for several key ministries relating to the Jewish settlements on Palestinian land.
Jewish Home's number two, Uri Ariel, is an ultra-nationalist settler slated to take over the housing ministry which plays a central role in settlement construction.
The party, which adamantly opposes a Palestinian state, is also likely to control the parliamentary finance committee which plays a key role in funding the settlements.