It passes for a truism in the Middle East that ceasefires are arranged as a courtesy to the combatants – enabling them to reload. Thus, when the six-months-old truce between Hamas and Israel expired this month it surprised no one when fighting resumed. What does surprise is that nobody seems to have lifted a finger to try to stop it.

The disproportionate scale of Israeli air strikes, in response to the pinprick provocations of the home-made rockets fired from Gaza at southern Israeli towns, is less surprising. It fits the Israeli doctrine of overwhelming force, which on Saturday claimed the highest number of Palestinian lives in a single day since Israel occupied the West Bank and Gaza in the 1967 Six Day War.

This level of violence goes beyond the assumed aims of both Hamas and Israel – to try to secure a new truce but from a position of strength – and looks set to create a full-blown crisis that could affect the outcome when Israelis and Palestinians go (separately) to the polls in coming weeks. Indeed, the ferocity of Israel’s assault on the crowded Gaza Strip is partly to be explained by the imminence of the vote. The governing Kadima party, led by foreign minister Tzipi Livni, and its Labour allies under defence minister Ehud Barak, fear being labelled weak and seem to be trying to out-hawk the irredentist Likud, led by Benjamin Netanyahu.

Mr Netanyahu, already ahead in the polls, must be chuckling. When Labour leader (and current president) Shimon Peres tried this tactic in 1996 – invading Lebanon and bombing Gaza – the Likud leader won the subsequent election.

But trying to crush Hamas from the air is self-defeating in other ways. It further enrages Arab and Muslim opinion against Israel and its US allies, and strengthens the appeal of Islamist radicals. And just as Hizbollah was aggrandised by Israel’s misfired 34-days war on Lebanon in 2006, so Hamas now stands to gain if it can hold its ground.

The Islamists are not blamed enough by Palestinians, not just for their sectarianism but for the vainglorious delusion they can emulate the deterrent power Hizbollah established by creating a balance of terror across the Israeli-Lebanese border. Palestinians elected Hamas three years ago because Fatah, their traditional vehicle of national aspiration, was sunk in corruption and had failed to end Israel’s occupation and create an independent state. Nevertheless, a majority of Palestinians still believes in a negotiated solution, not Hamas’ violent tactics.

Yet Israel, backed by the US and the mute assent of Europe, has sought to isolate Hamas. After Hamas fought it out with Fatah and ejected it from Gaza 18 months ago, the 1.5m Gazans have suffered a blockade rationing food, fuel and medicine entering the enclave.

This policy makes Palestinians dependent on Hamas for basic needs. It makes violence an attractive alternative both when (Hamas) truces fail to lift the blockade and (Fatah) peace talks fail to deliver peace. It is in any case delusional for Israel to imagine it can make peace with half the Palestinians while waging war on the other half.

It must be remembered that the root cause of the Israeli-Palestinian conflict is the Israeli occupation – which Israel’s 2005 withdrawal from Gaza was meant to consolidate, through its subsequent expansion of Jewish settlements in the West Bank and Arab east Jerusalem.

With a lame duck administration in Washington, it is hard to see who will de-escalate this crisis. But Fatah and Hamas need now to put aside their differences and agree a platform for talks with Israel leading to a Palestinian state on the West Bank and Gaza with east Jerusalem as its capital. Once Barack Obama takes office he should lay out this solution – contained in the December 2000 “parameters” of Bill Clinton – and start pressing both sides to enact it. He has a unique opportunity to influence both sides – and maybe even persuade them to elect leaders able to close the deal.