Far-right party leader Naftali Bennett threw his crucial support on Sunday behind a "government of change" in Israel to unseat Prime Minister Benjamin Netanyahu, in what would be the end of a political era.

Bennett's decision, which he announced in a televised address, could enable opposition chief Yair Lapid to put together a coalition of right-wing, centrist and leftist parties and hand Netanyahu his first election defeat since 1999.

Lapid, head of the centrist Yesh Atid party that finished second to Netanyahu's right-wing Likud in an inconclusive March 23 national ballot, faces a Wednesday deadline from Israel's president to announce a new government.

Lapid's chances of success have rested largely with Bennett, a former defence chief whose Yamina party's six seats in the 120-member parliament are enough to give him the status of kingmaker.

Under a prospective power-sharing deal, Bennett would replace Netanyahu, the 71-year-old head of the Likud party, as prime minister and later give way to centrist Lapid in a rotation agreement.

"It's either a fifth election, or a unity government," Bennett, 49, said in his speech, explaining his decision to partner with Lapid.

Israel has held four inconclusive elections since April 2019.

The new coalition's diverse members would have little in common apart from a plan to end the 12-year run of Netanyahu, Israel's longest-serving leader, now on trial over corruption charges he denies.

An anti-Netanyahu coalition would be fragile and require outside backing by Arab members of parliament who oppose much of Bennett's agenda, which includes more settlement building in the occupied West Bank and its partial annexation.