Jerusalem (CNN) -- Faced with a choice that could tear apart his coalition government, Israeli Prime Minister Benjamin Netanyahu is considering holding early elections this fall, his spokesman, Mark Regev, said Sunday.

While Regev said no decision has been made, political pressure for early elections has been building in recent weeks from both within the Israeli government and the main opposition party, Kadima.

Netanyahu´s primary coalition partner, Foreign Minister Avigdor Lieberman, is expected to introduce a new bill May 9 that would force Israeli Arabs and Ultra Orthodox Jews to serve in the Israeli army or participate in national service programs.

Both groups have historically been exempt from duty, but in the past year there have been increased public demands that they take an equal share of the burden.

Lieberman told Israeli Channel 2 this weekend that "our obligation to the coalition is over" if his political demands are not met. That could trigger a call for early elections.

Lieberman´s proposed law would face vigorous opposition from the other main part of Netanyahu´s government -- Ultra Orthodox parties, who oppose any change to the status quo.

It means Netanyahu may have to side with either Lieberman or the Ultra Orthodox parties, a choice that could anger the other side enough to bring down his government.

The prime minister indicated Sunday he may seek to back Lieberman´s draft and accommodate public demand. He met Sunday with army reservists and expressed his support for replacing current legislation with a "more egalitarian and just law."

Netanyahu promised to submit the new law himself and said it will also include civilian service duty for Arab Israeli citizens.

"This must be done without setting public against public. The change will entail expanding frameworks and increasing budgets. This is high on the list of priorities for the security of the state," he said.

Meanwhile, Shaul Mofaz, who took over as head of Kadima last month, is calling for elections in October and said he wants to hold talks with all parties on a new election date.

"Netanyahu has failed and it is time to bring back the hope for the people of Israel," Mofaz said Saturday. "The days of Netanyahu´s government are numbered."

October 2013 is the official date for the next parliamentary elections but both the parliament and prime minister have the power to move them to an earlier date. (© 2012 Cable News Network 04/29/12)