"Up until the last minute anything can change, but as of now he is expected to announce early elections," Likud party spokeswoman Noga Katz told AFP.
Netanyahu, who has been observing the traditional week-long mourning period after the death of his father, is to make a speech calling for the vote to be brought forward from October 2013, at a meeting of his Likud party in Tel Aviv on Sunday evening.
The address will end months of speculation about whether the premier would seek to capitalise on his popularity and formally confirm the early election date mooted by Israeli officials, including Netanyahu's coalition chairman Zeev Elkin.
"The consensus of most of the coalition parties and part of the opposition is that the election will take place on September 4," Elkin told Israeli public radio on Wednesday.
Observers had long suggested Netanyahu would seek to bolster his standing ahead of painful budget cuts expected later this year and the US presidential election in November.
His decision is believed to have also been influenced by a fight within his coalition over a contentious law on the military service of ultra-Orthodox Jews.
The so-called Tal Law, which allowed ultra-Orthodox Jews to defer their service, is strongly opposed by the staunchly secular Israel Beitenu party headed by Netanyahu's Foreign Minister Avigdor Lieberman.
Netanyahu has pledged to replace the law, which expires this year, with a more "egalitarian" rule, but is caught between Israel Beitenu and the ultra-Orthodox factions in his coalition, who adamantly oppose military service.
But polls show that the premier could hardly have picked a better time to seek re-election, with surveys showing he easily outstrips his rivals for the office of prime minister.
A poll published in the Haaretz daily on Thursday showed Netanyahu commands more support than his next three rivals put together, with 48 percent of Israelis backing his re-election.
His Likud party also looks set to sweep the polls, increasing its standing in the 120-seat Knesset and having its choice of parties with which to form a coalition.
Polls, including a latest survey published by the Maariv daily on Friday, consistently show Likud netting around 31 seats, up from the 27 it currently holds.
The Maariv poll showed the Labour party taking 18 seats, up from the 13 it won in the last elections, with Israel Beitenu seeing its 15 seats fall to 12.
The Kadima party, which won the most seats in the last election but failed to form a coalition, looks set for a crushing defeat, with its 28 seats reduced to just 11.
The newly-formed centrist Yesh Atid (There is a Future) is also expected to win around 11 seats.
The biggest uncertainty surrounding the vote is the shape of Netanyahu's eventual coalition. Polls show the smaller conservative and religious parties he is in government with now will win enough seats to rejoin him in power if he chooses.
But Labour, Kadima and Yesh Atid have also expressed some willingness to join a new Netanyahu government.