Key Israeli politician Avigdor Lieberman has refused to endorse a candidate for prime minister, blaming both the contenders engaged in a tense standoff that has paralysed Israeli politics and pushing the country towards a likely third election in less than a year.

His comments came ahead of a midnight deadline for prime minister Benjamin Netanyahu’s rival, Benny Gantz, to form a coalition. Without Mr Lieberman, he appears unable to secure the required majority in parliament to be prime minister.

If Israel is forced into a third election, it would be entering uncharted waters, with opinion polls already predicting a similar deadlock.

A new campaign could benefit the embattled Mr Netanyahu, who is expected to be indicted on corruption charges in the coming weeks. He would be best-positioned to fight any charges from the prime minister’s office.

Mr Lieberman, who heads a small, secular ultranationalist party, triggered the September election after refusing to join Mr Netanyahu’s traditional allies of hardline and religious parties following earlier elections in April.

Avigdor Lieberman
Avigdor Lieberman (Oded Balilty/AP)

The repeat vote left Mr Netanyahu’s Likud and Mr Gantz’s Blue and White party both short of a required majority in the 120-seat parliament without Mr Lieberman’s support.

Mr Lieberman, who hails from the former Soviet Union, has objected to the outsized influence of ultra-Orthodox religious parties and has urged the two contenders to join him in a unity government as a way out of the stalemate, but they have refused to bend on their core conditions for such an arrangement.

After weeks of negotiations, Mr Lieberman told reporters he would not align with either party on its own.

“I made every effort. I turned over every stone,” he said. “There were no significant gaps, they were mainly personal gaps and after it all, at least for now, it seems we are heading for another election.”

He said he objected to Mr Netanyahu’s alliance with “messianic” religious parties, while he also accused Mr Gantz of reaching out to religious parties and not negotiating in good faith.

“Who is to blame in this situation? Both parties together,” he said. “There was an impressive blame game from both parties, but at the end it was a blame game, with no real will to take tough and dramatic decisions.”

Mr Gantz was given the opportunity to form a government last month after Mr Netanyahu failed in the task.

A former military chief, Mr Gantz has a midnight deadline to present a potential coalition government. If he fails, as expected, the country enters the final 21-day period for any candidate to present a majority before new elections are called.