Israel's opposition parties will join forces for the first time since the April 9 election to organize a demonstration on Saturday night against the Prime Minister Benjamin Netanyahu’s bid to legislate himself immunity from prosecution, but Arab parties will not be participating.

Kahol Lavan, Labor and Meretz are working together to bring people to the Tel Aviv Museum plaza to protest against the proposed legislation. Although Arab parties will not have official representation or a speaker on the podium, Hadash-Ta’al said their activists will be there.

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Hadash members say party head Ayman Odeh was disinvited even though he had agreed to speak at the rally, while other Arab parties said they had not been asked to participate.

A senior member of Kahol Lavan said the organizers asked Odeh two weeks ago if he would speak at the rally. Odeh only gave his affirmation at the beginning of this week, but was told the list of speakers had already been finalized.

But sources among the organizers said there were objections to having Odeh speak at the rally, resulting in his invitation being revoked.

Odeh declined to comment. But another Hadash lawmaker, Ofer Cassif, denied the report that Odeh’s reply had been delayed and said it was the organizers who decided to exclude him.

United Arab List-Balad leader Mansour Abbas said he would have agreed to participate in the demonstration had he been asked. But the party wasn’t invited to join the rally and will not be taking part in it.

“I know their positions are mostly right-wing but we wage a joint struggle for democracy in the Knesset, so I see no problem in taking part in the rally, if the central issue is fighting corruption and defending democracy,” Abbas said. “But regrettably, nobody approached us on the matter.”

The demonstration will be the first public test of the ability of Kahol Lavan’s Benny Gantz to lead the opposition. The museum plaza was chosen rather than the larger Rabin Square to avoid photographs of empty spaces in the media if the crowd is not great.

Previous rallies associated with the opposition at Rabin Square have attracted 30,000 protesters at the most. This time, the organizers won’t say how many participants will mark the event as a success.

“Obviously if the square is empty it will be a failure. But if we fill it up, we can proceed to other moves,” an opposition source said.

One way or another, Kahol Lavan, Labor and Meretz are making efforts to get the public out en masse with text messages, emails and advertising on the social media. Yesh Atid said it was organizing transportation to the rally from 21 different locations, from Nahariya and Tzemach junction in the north to Be’er Sheva in the south.

The demonstration’s Facebook page says dozens of the busses are already full. The organizers are also working on bringing right-wing voters to the event.

“This isn’t a left-wing demonstration and it’s important for us to enable Likud voters who are shocked by the expected breach to the rule of law to come and protest,” one of them said.

The yet unpublished speakers’ list will include Gantz, Yair Lapid, Labor Chairman Avi Gabbay and Meretz Chairwoman Tamar Zandberg. Other public figures and organization leaders are also expected to speak.