Before last summer, Prime Minister Benjamin Netanyahu appeared unassailable. Isaac Herzog, the head of the Labour opposition, got less than 10 per cent support in public opinion polls. Now, Likud and the Herzog-Livni Zionist Union run neck-and-neck.
There are numerous reasons for Mr Netanyahu's sudden vulnerability. The social protests of 2012 put the issues of social equality and economic hardship on the public agenda. Mr Netanyahu promised to address them but nothing was done, causing anger among young voters (and their parents).
Moreover, heading an unwieldy coalition, it appeared that Mr Netanyahu was unable to effectively control the government's policies, with ministers pursuing their own agendas.
The continuing deterioration of Israel's international standing, as well as Mr Netanyahu's public disagreements with President Barack Obama, made many Israelis uncomfortable with the direction of the government. Was it worth alienating Israel's best friends with continued settlement building?
And last but not least: the problematic outcome of the Gaza war in the summer came back to haunt the Prime Minister, who has consistently vowed to "crush Hamas". The 2014 war did not crush Hamas, but did visit terrible punishment on tens of thousands of civilians, exacerbating criticism of Israel.
If Herzog wins, expect a fundamental change in atmospherics
What appeared to be Mr Netanyahu's obsession with Iran's putative nuclear weapons at a time when he showed no adequate response to missiles from Gaza deeply damaged his credibility. For the first time, more and more people started feeling that Bibi may, after all, be a hollow windbag. Recently published tidbits on the sultanistic lifestyle of the Netanyahu family did not help.
At the same time, the emergence of the Zionist Alliance as a joint list of Herzog's Labour and Tzipi Livni's Kadima changed the political discourse. For the first time, there appeared a credible alternative to which Mr Netanyahu may be vulnerable.
Even Mr Herzog's laid-back style - initially compared negatively with Mr Netanyahu's flowery rhetoric - started to appear as an asset, with comparisons to Levi Eshkol, the PM who led Israel to its greatest victory in 1967: no Demosthenes he, but a pragmatic yet decisive leader; also a mensch.
All polls suggest a draw, with neither Likud nor the Zionist Alliance getting more than 25 seats each in the 120-member Knesset. Coalition negotiations will be exhausting, with Likud enjoying the advantage of having more possible coalition partners.
A centre-left coalition may need the votes of a united Arab list, which brings together communists and Islamists: not comfortable partners for Herzog.
A final caveat: even if Mr Herzog becomes the next prime minister, to imagine that this leads automatically to a final status agreement with the Palestinians is an illusion; the gaps are too deep. Yet there will be a fundamental change not only in atmospherics, but also in substance. To have an Israeli government viewing the PA as a possible - even if difficult - partner is very different from the Netanyahu rhetoric, which has consistently demonised all Palestinians. For an Israel destined to live in the Middle East, not to feel that there is no hope for a rapprochement will be a major respite from the constant feeling of everlasting strife.
After all, the national anthem, Hatikva, means hope. But the jury is still out.
Shlomo Avineri is Professor of Political Science at the Hebrew University. His recent book is 'Herzl: Theodor Herzl and the Foundation of the Jewish State' (Weidenfeld)