The law gives President Reuven Rivlin a lot of leeway in whom he nominates to form a government. Mr. Rivlin, an old rival of Mr. Netanyahu, said he would act as all former presidents did and task whomever had the best chance of forming a government that would gain the confidence of the new Parliament.

The divisions were playing out noisily on Monday in the street outside the Jerusalem District Court, where dozens of protesters for and against Mr. Netanyahu had gathered at opposite sides of the courthouse.

Anti-corruption protesters held up placards listing the charges against the prime minister and chanted through megaphones. On a small stage, lawmakers from his conservative Likud party claimed that the legal process was being used to unseat Mr. Netanyahu after his opponents failed to do so through the ballot box.

“In the justice system, our choice of ballots is being assassinated,” declared Galit Distel Etebaryan, a newly elected Likud lawmaker.

The drama of the State of Israel v. Benjamin Netanyahu revolves around three cases in which Mr. Netanyahu stands accused of trading official favors in exchange for gifts from wealthy tycoons. The gifts ranged from deliveries of expensive cigars and Champagne to the less tangible one of flattering coverage in leading news outlets.

The first case being tried, known as Case 4000, is the weightiest and the only one in which he has been charged with bribery.

According to the indictment, Mr. Netanyahu used his power as prime minister and communications minister at the time to aid Shaul Elovitch, a media tycoon and friend, in a business merger that profited Mr. Elovitch to the tune of tens of millions of dollars. In return, Walla, a leading Hebrew news site owned by Mr. Elovitch’s telecommunications company, provided the Netanyahu family with favorable coverage, particularly around election time.

The long-anticipated court session opened Monday with a lengthy speech by the chief prosecutor, Liat Ben-Ari. Mr. Netanyahu, who was required to be present, sat at the back of the courtroom.

Describing the case as “significant and grave,” Ms. Ben-Ari said that according to the indictment, Mr. Netanyahu, listed as “Defendant No. 1,” had “made improper use of the great governmental power entrusted to him,” to demand favors from the owners of media outlets to advance his personal affairs, including “his desire to be re-elected.”

Mr. Netanyahu left the court before the first witness, Ilan Yeshua, the former chief executive of Walla, took the stand. With more than 330 witnesses expected to appear, the trial could go on for years.

Mr. Yeshua described how he would receive instructions from go-betweens to post or highlight positive stories about Mr. Netanyahu and his wife, Sara, as well as items that cast his political rivals in a negative light.

He said he relayed the requests to the newsroom and described his daily and hourly struggles with editors as a “nightmare.”

While many Israelis viewed the trial as a triumph for the rule of law, critics said it was a distortion of justice, arguing that all politicians seek positive media coverage.

“Even if, after several years and tens of millions of shekels, the trial ends, as it should, with an acquittal for all parties, the country will bear the costs of this politicization of criminal law for many years to come,” Avi Bell, a professor of law and a senior fellow at the Kohelet Policy Forum, a conservative leaning, Jerusalem-based think tank, said in a statement

The parallel political process underway at Mr. Rivlin’s official residence did little to dispel the sense that Israel remained trapped in a loop of political uncertainty and instability.

One after the other, delegations of the 13 parties elected to the Knesset came Monday to announce which candidate they endorsed to form the next government.

Mr. Netanyahu, whose Likud party won 30 seats in the 120-seat Parliament, was assured of 52 recommendations from his right-wing and ultra-Orthodox allies, well short of a majority of 61 but still more than any one of his opponents would likely muster.

The remaining 90 parliamentary seats are split between a dozen other parties. Yair Lapid’s centrist Yesh Atid party came in second, with 17 seats. All the others resulted in wins of single digits.

The political stalemate has been compounded by Mr. Netanyahu’s refusal to step aside while on trial and by the incoherence of the anti-Netanyahu camp, made up of parties with clashing agendas. Some have ruled out sitting in a government with others.

Many analysts believe the deadlock will lead to a fifth election, though some small parties that now hold a lot of power would risk elimination in any speedy return to the ballot box.

The sheer number of parties is a sign that “Israeli cohesion is unraveling,” said Yedidia Stern, president of the Jewish People Policy Institute in Jerusalem.

“Israeli society is very fragmented,” he said. “The lack of cohesiveness in Israeli society will not disappear just because an election goes this way or that.”