Parliament on Monday set polling day for March 17, just over two years after Netanyahu's right-leaning coalition took office, and following a spat in which he fired two ministers and called the early vote.
The challenge will come from an alliance between Isaac Herzog's Labour party and the centrist HaTnuah of former justice minister Tzipi Livni, whom Netanyahu dismissed along with finance minister Yair Lapid.
Such a centre-left alliance would win 24 seats in the 120-member Knesset, polls published in Yediot Aharonot and Maariv newspapers said Friday, with the dailies respectively projecting 23 and 20 seats for Netanyahu's Likud.
"Unlike in the previous elections (January 2013), we have a common goal -- to replace Mr Netanyahu," Livni said in a television interview before the Labour-HaTnuah alliance was announced.
The latest poll numbers ignore the strong likelihood of Likud teaming up with other rightwing parties.
They do not indicate a shift in public opinion but rather simply the sum of each party's projected seats in a country that still favours the right, according to Denis Charbit, a politics professor at Israel's Open University.
"By making the alliance with HaTnuah, Labour is becoming once again the centre of gravity for the left and a credible party for government," Charbit said.
"But in general, political forces remain largely unchanged in terms of support, with the rightwing bloc favoured. It can still count on having around 70 MPs against the left and centre's 50 combined."
The success of Labour-HaTnuah will depend heavily on post-election moves by Moshe Kahlon, an ex-Likud minister who last month formed his own centre-right party Kulanu (All of Us), and by Foreign Minister Avigdor Lieberman, head of the far-right Yisrael Beitenu.
"Kahlon and Lieberman will find themselves acting as a pivot after the elections, and both have said they want to end the Netanyahu era," Charbit said.
Signup to our newsletter and follow us on Facebook and Twitter!
While the premier is looking to secure a fourth term, some commentators say that whatever the outcome of the vote, he is sure to go.
"His authority has dissipated; his performance has become flawed; his political instincts have dulled; he has become fed up with his ministers and they have become fed up with him," Nahum Barnea wrote in the mass-circulation newspaper Yediot Aharonot.
'ATTEMPT TO OUST LIKUD'
Netanyahu himself is aware that many would like him out of government.
"There's a clear attempt to kick out the Likud and replace it with the left," he was quoted on public radio as telling his party on Thursday.
"It's the goal of many parties and media officials."
Netanyahu has indicated he might seek alliances with ultra-Orthodox parties, considering them "natural allies", and Yisrael Beitenu as well as the hardline Jewish Home headed by Economy Minister Naftali Bennett.
Bennett strongly opposes negotiations with the Palestinians and supports settlement expansion in the West Bank -- a sticking point that has scuppered round after round of peace talks.
Observers say a centre-left government would be far more likely to resume peace talks as the international community calls for negotiations to avoid further escalation.
Livni was Israel's chief negotiator during the last round of US-brokered talks, which collapsed in April mainly over the issue of settlement building.
The left has also criticised Israel's immigration policy, after Netanyahu's government pushed for a harsher crackdown on African asylum-seekers, which it refers to as "infiltrators".
A law passed in March which raises the threshold of votes parties require to be represented in parliament could see many parties making alliances.
Israel's next general election had been due to take place in 2017, and many commentators have called the upcoming vote "unnecessary".