With just over two weeks to go before the 2013 Knesset elections, the center-left parties are trying to form a unified bloc that would prevent Likud Prime Minister Benjamin Netanyahu from forming a right-wing coalition. Labor party Chairwoman Shelly Yachimovich and Hatnuah party Chairwoman Tzipi Livni were set to meet on Sunday, but it seems their efforts may be stymied by the third center-left party, Yesh Atid, headed by Yair Lapid.

Appearing on Channel 2's "Ulpan Shishi" Friday night program, Livni issued a call to Yachimovich and Lapid to meet with her in an attempt to establish a "united front" that would prevent the prime minister from putting together a coalition after the elections.

"We have to work together to replace Netanyahu or create a bloc that will prevent him from establishing an extremist right-wing ultra-Orthodox government," Livni said during the interview.

Meanwhile, sources in the Likud party expressed concern over the involvement of President Shimon Peres, after he recently met separately with Lapid, Livni and Yachimovich. The Likud sources suggested that Peres may have pushed the three center-left parties to unite in an attempt to reduce Netanyahu's chances of heading the next government.

Livni proposed the idea of the three parties uniting after meeting with Peres on Friday.

"The president has woken up. Now he is saying that things have to be different. He is everyone's president. He met with Yair Lapid, but not only with him. It's because he cares. He is concerned and finally said so out loud. He thinks and expresses what everyone is worried about," Livni said.

"For two years I saw the president crisscrossing the world saying that Netanyahu would bring peace. I knew it wouldn't happen and I didn't like his saying it, but I refrained from attacking him publicly. But now he has sobered up and is saying that things need to change. Is that not a good thing? Why is the Likud trying to silence him?"

Senior political sources on the Right told Israel Hayom Saturday night that "the president intends to do everything in his power to give the Left the authority to compose the next government."

However, the President’s Residence issued a statement in response, saying: "The president is not involved in any kind of political maneuvers. This would be opposed to the nature of his job and his worldview. The president has held meetings over the past few days with party leaders who seek to learn from his experience. His purpose is not to interfere in the election process. The president has also met with the prime minister and the heads of Shas. In keeping with this policy, the president recently agreed to meet with both Livni and Lapid."

Lapid called the right wing's accusations against Peres "ludicrous" on radio shows Sunday morning.

Peres, along with the Central Election Committee Chairman Elyakim Rubinstein, was expected to kick off a public relations campaign on Sunday to encourage citizens to vote.

One person who freely admits that he is trying to unite the center-left parties against Netanyahu is former minister Haim Ramon, who left the Knesset after being found guilty of sexual transgressions, and who co-founded Hatnuah.

"For a month I have been trying to build a center-left bloc, and I hope I succeed," Ramon said at a meeting of the Commercial and Industrial Business Club in Tel Aviv. "The three parties combined will get more than 40 mandates, more than the Likud."

On Friday’s television interview, Livni said, "I am calling on Shelly and Yair, let's unite. Let's sit together." Just a few minutes later, during the commercial break, she received a text message from Yachimovich, inviting her to meet.

Lapid also agreed to meet with Yachimovich and Livni, but said he was not interested in uniting to block a right-wing coalition.

"Shelly and Tzipi want us to announce that we will not enter the government, but what will come of that?" Lapid wrote on his Facebook page. "A [strictly] right and ultra-Orthodox government? So we are showing leadership and proposing the opposite. Instead of ignoring the reasonable possibility that Netanyahu will be the one to compose the next government, let's enter the government together and ensure that it is reasonable and sane. Doesn't that make more sense?"

In an interview on Channel 2 on Saturday, Lapid said, “I don't like it when people act under pressure. In my view, it is a little strange that she [Livni] had to make her announcement on television in such a dramatic way. I am not interested in joining a bloc that would block a right-wing coalition, because I am not in the habit of boycotting individuals or parties. I don't understand Livni. Would she form a government with Hanin Zoabi? I don't want a far-right ultra-Orthodox coalition either, and I would not enter such a coalition on my own alongside the Likud, Orit Strook and Eli Yishai."