Former Kadima leader Tzipi Livni is set to announce her decision this week whether she will run in the January elections, and Labor Chairwoman Shelly Yachimovich urged her on Saturday to join Labor and avoid fragmenting the center-left bloc.

Livni is said by close associates to have decided to join the race, but has not officially announced her decision.

"Those who want to bring about a new government in Israel, replace [Prime Minister] Benjamin Netanyahu and establish a better government for the country should not build new parties that will always remain small, compete with one another for the same votes and fail to present a viable alternative," Yachimovich said at a cultural event for elderly residents of Tel Aviv on Saturday.

"The only alternative to Netanyahu is the Labor party, under my leadership," Yachimovich said. "Those who want to bring Netanyahu down and strengthen the center bloc must join Labor, rather than establish splinter parties."

Yachimovich said the forging of new parties would not damage Labor. "Since we will still remain the leading party, anyone who values the replacement of the government must join the Labor party that I head."

The Labor chairwoman even tried to pressure Livni to join her via social networks. On her Facebook page, she wrote, "Tzipi, don't divide the center. Join us, and together we will put an end to Netanyahu's rule."

At Saturday’s event, Yachimovich pointed out that since Livni had left politics she had courted her and asked her to work together, making her some very "respectable offers."

According to Channel 10, Yachimovich offered Livni the number two spot on Labor's list of candidates for the Knesset, but Livni demanded that the two take turns as prime minister in the event that Labor wins the right to form the next government.

At a conference sponsored by the Interdisciplinary Center in Herzliya two weeks ago, Livni said there was great importance in maintaining a united bloc. "I have no interest in dividing the bloc to which I belong,” she said. “There be would be no wisdom in doing that."

Channel 2 reported on Saturday that if Livni decided to run in the elections at the head of her own party, the party might be given the name "National Responsibility."

The report also said Livni would meet with former Prime Minister Ehud Olmert on Sunday to discuss a joint ticket. They have already met twice recently, and Livni said she was waiting for Olmert to announce his decision on his political comeback before she announced her own decision.

Olmert postponed his decision at the outbreak of Operation Pillar of Defense and is expected to declare his intentions in coming days.