Israeli Prime Minister Benjamin Netanyahu faced calls to resign over a corruption scandal on Friday, as senior government colleagues publicly declared support after some signs of cracks in party loyalty.

Israeli Attorney General Avichai Mandelblit on Thursday formally indicted Netanyahu on charges of bribery, fraud and breach of trust after a three-year investigation. 

The 70-year-old leader of the Likud party accused prosecutors of staging "an attempted coup."

Can Netanyahu hold on?

Netanyahu's ability to lead a country mired in political crisis, after two inconclusive elections this year that failed to produce a government, is being questioned. 

The centrist Blue and White Party headed by Netanyahu's main rival, Benny Gantz, issued a statement calling on him to "immediately resign from all ministerial positions in the government."

The party - which has 33 of parliament's 120 seats to Likud's 32 - said its lawyers had formally approached the prime minister and attorney general's offices saying it was "imperative" that Netanyahu step down.

A poll aired by Israel's Channel 13 TV found that 56 percent of Israelis believe Netanyahu cannot continue to govern after being indicted. A total of 35 percent said he can and nine percent were undecided. 

What happens next?

Under Israeli law, the veteran leader is under no obligation to step down as prime minister. But with Israel heading toward a likely third election in less than a year, Netanyahu could soon find himself in the difficult position of trying to win an election while preparing to be prosecuted. 

The support of his Likud party colleagues is likely to be crucial to Netanyahu's chances of staying in power. Two Likud lawmakers publicly broached holding a party leadership contest on Thursday, but even such mild expressions of disloyalty upset loyalists.

But Israel's election schedule could yet work against Netanyahu, Israel's longest-serving prime minister after 10 successive years in power plus three years in office in the 1990s. 

President Reuven Rivlin on Thursday set a three-week deadline for lawmakers to nominate a new candidate from their own ranks to try to form a new government after Netanyahu and Gantz both failed to do after April and September elections. 

If that also fails to produce a government, an election will be triggered in three months.

(With input from Reuters)