Benjamin Netanyahu’s pledge to expand Israeli sovereignty over the occupied West Bank was short on specifics. It looks, at first glance, like a typical piece of Bibi electoral gamesmanship, designed to attract rightwing and nationalist voters – and boost his hopes of tipping the balance in Tuesday’s closely fought national polls.

But Netanyahu is not simply playing politics. He has previously flirted with annexation of Judea and Samaria, as the Israeli government calls the West Bank, as part of an apparent drive to prevent the creation of a viable Palestinian state. A Haaretz poll last month found 42% of Israelis supported West Bank annexation. Netanyahu also recently suggested that Israel, in extremis, might reoccupy the Gaza Strip.

Israeli commentators have dubbed Netanyahu “the undertaker of the two-state solution” – the longstanding plan for two separate states co-existing side-by-side, which has hitherto underpinned the internationally sponsored peace process to resolve the Israel-Palestine conflict. If implemented, his latest proposals would permanently bury it in an unmarked grave.

A rightwinger instinctively opposed to Palestinian self-determination, Netanyahu has a history of changing tack as political circumstances demand. In the 2009 elections, he supported a demilitarised Palestinian state. In the 2015 polls, he declared his own policy “null and void”, claiming Israel lacked a partner for peace.

Now, exploiting old, visceral fears that the Palestinians’ true aim is not independent statehood but Israel’s destruction, he has gone a big step further, towards the contentious biblical idea of “Greater Israel”. Yet his gambit could backfire if it galvanises the demoralised Israeli left, and Israel’s Arab citizens – comprising 17% of the electorate – to turn out in larger numbers in a bid to defeat him and his hard-right allies.

His personal inclinations aside, it is unlikely Netanyahu would have floated so potentially disruptive an idea without a nod and a wink from Donald Trump. In the past, when Netanyahu claimed to have US backing for annexing West Bank territory containing the major Israeli settlement blocs, the White House publicly disavowed him.

But times are changing. Trump’s formal recognition of Israeli control over all of Jerusalem, ignoring Palestinian counter-claims, and over the Golan Heights, seized by force from Syria in 1967, has emboldened Israel’s leader. So, too, have Trump’s punitive measures against the Palestinians, including cutting bilateral financial support and designated UN funding for Palestinian refugees.

Trump may not be ready to say so on the record, as yet, but given the dramatic rightwards lurch in US policy since he took office, it is wholly conceivable he would back annexation moves, especially if limited to the principal illegal settlements where tens of thousands of Israelis already live. It is possible annexation will form part of the long-delayed US “peace plan” being developed by Trump’s son-in-law, Jared Kushner – and already rejected by the Palestinians.

If Netanyahu wins again and pushes ahead – a big “if” given current volatility and the likely weakness of any post-election coalition – resistance, political and physical, will be fierce. A concerted move to assimilate the West Bank would be likely to provoke a strong reaction from Palestinian residents both there and in Gaza. Any resulting violence could draw in Hezbollah in Lebanon and even Iranian forces in Syria.

European and non-aligned states would also be certain to oppose annexation as a dangerous violation of international law and UN resolutions dating back more than half a century. Trump’s Golan shift was widely criticised, for example, for giving post-facto justification to Russia’s illegal annexation of Crimea in 2014.

Jeremy Ben-Ami, the president of the US-based progressive advocacy group, J Street, said Netanyahu’s statement was intended to sabotage the creation of a Palestinian state and potentially endangered Israeli lives.

“If carried out, even a partial annexation would be a disastrous blow to Israel’s security and democracy – and a severe violation of international law … Israel cannot rule permanently over millions of Palestinians while denying them equal civil and political rights,” Ben-Ami said.