Members of Israeli Prime Minister Benjamin Netanyahu's Likud party are slamming last week's merger deal with coalition partner Avigdor Lieberman's Yisrael Beiteinu party to run as a team in the upcoming elections.

Netanyahu is set to meet with leading Likud activists, in a bid to get their consent for the move, ahead of Monday's internal party convention.

Netanyahu, who spoke Sunday morning with the Likud ministers during a weekly meeting, said Lieberman can choose among the foreign, defense and finance portfolios.

However, "as I gather, he's interested to stay as the foreign minister," Netanyahu told his ministers, according to the Ynet news website.

The Walla news site said Lieberman and Netanyahu had in fact agreed that the former would remain in his current role in a future government.

Objectors to the merger between the two parties have collected 400 signatures calling for a confidential ballot on the issue, which may work against Netanyahu.

Several ministers said the atmosphere during the meeting was very tense.

"There was a great silence of protest. No one agreed to talk, as if there was no agreement with Lieberman. It was embarrassing," one minister told Ynet.

Finance Minister Yuval Steinitz reiterated that Lieberman would stay as foreign minister in the next government, The Jerusalem Post reported.

Former Kadima party chief Tzipi Livini on Sunday attacked the idea that Lieberman could serve as defense minister, calling such a slot no less than an "existential threat."

"Netanyahu is losing his senses and is gambling with Israel's security out of political and survivalist considerations," Livini told the newspaper.

"Lieberman was the one who threatened to bomb the Aswan dam (in Egypt). Is this the defense minister that Israel needs right now? The answer is clear," she added.

On Thursday, Netanyahu and Lieberman announced they will be running in a joint list for the Jan. 22 elections.

Both Netanyahu and Lieberman have denied speculation that Lieberman will rotate with Netanyahu in the premiership role, in case the two win the elections.