Isrseli Prime Minster Benjamin Netanyahu gives an announcement on September 10, 2019 in Ramat Gan, Israel. Amir Levy | Getty Images News | Getty Images

Israeli citizens will vote for the second time in less than six months on Tuesday, in an election that is widely seen as a de facto confidence vote on Prime Minister Benjamin Netanyahu. The ballot comes at a precarious time for the country's longest serving prime minister, with the right-wing incumbent facing formidable challengers to his reign and possible criminal charges in three corruption cases. The most recent opinion polls showed Netanyahu's Likud party running neck-and-neck with the centrist Blue and White party, headed by former military chief Benny Gantz. Neither are expected to secure a majority. It means the real battle for power is likely to take place immediately after all the votes are counted, when negotiating begins to form a coalition government. "The election is about three issues: Bibi, Bibi, and Bibi," Henry Rome, senior analyst at political risk consultancy Eurasia Group, told CNBC via email, referring to Israel's leader. "It's a referendum on the long-running prime minister, as was the April race."

Why is Israel having another vote?

In April's election, Netanyahu and his right-wing allies appeared to come out ahead. The result was heralded as a convincing victory for the country's right wing and religious community — one which threatened an even more fraught relationship with Palestine. However, Netanyahu failed to convert a bloc of right-wing allies into a majority government after he lost support from his former hawkish defense minister, Avigdor Lieberman. To give himself another chance, Netanyahu dissolved parliament. The move has set the country on course for two national polls in one year for the first time in its history.

Who's going to win?

"It is very evenly balanced," Keren Uziyel, an Israel analyst at the Economist Intelligence Unit (EIU), told CNBC via telephone. Netanyahu appears to have maintained support among his core base "but the added joker this time is that the party of Lieberman will be the deciding vote," Uziyel said. Lieberman is seen by many as having a pivotal role when it comes to negotiating a new majority government. The last opinion polls taken before election day showed the ultra-nationalist leader of the Israel Beitenu party was set to win several more seats than last time.

An Israeli woman casts her ballot during Israel's parliamentary election, at a polling station in Rosh Haayin, on September 17, 2019. JACK GUEZ | AFP | Getty Images

It is likely to mean Liberman is awarded kingmaker status, giving him a say over who becomes the country's next leader. There are many potential scenarios in which both Netanyahu and Gantz come out ahead, but it remains unclear whether another political stalemate can be avoided.

Why does it matter?

Ahead of the vote — and in a bid to shore up support among right-wing voters — Netanyahu promised that if re-elected, he would extend Israeli sovereignty over Jewish settlements and up to a third of the occupied West Bank. The controversial move would encircle the 2.5 million Palestinians living there and make a two-state solution more difficult. Israel has occupied the West Bank since 1967. Past U.S. administrations have viewed the Israeli settlements in the West Bank as an impediment to a possible peace deal between Israel and the Palestinians, and much of the world considers the settlements to be illegal. Tweet 1 On Saturday, President Donald Trump said he had held talks with Netanyahu to discuss the possibility of moving forward with a mutual defense treaty between the U.S. and Israel. The U.S. president said via Twitter that he looked forward to continuing those discussions later this month, on the sidelines of the United Nations General Assembly session in New York. "This much touted peace process is not going anywhere anytime soon. I don't think the peace process will be a priority for the U.S. and Israel. Most Israelis, to a greater or lesser extent, feel insulated to what's happening in Palestine," the EIU's Uziyel said. "I don't envisage him annexing the Jordan Valley in two weeks' time."

What happens next?