Shelly Yachimovich’s leadership of the Labor Party is likely to be challenged after its disappointing election performance.

MK Eitan Cabel, a former party secretary-general who is third on the party list, will soon announce his intention to make his bid for party chairmanship, sources told Yedioth Ahronoth Sunday.

Cabel was one of the first senior party officials who expressed his disappointment with the party’s performance in the elections, in which it won 15 seats. Labor won 13 seats in the 2009 elections, but polls had shown it heading for 20 at one stage in the recent campaign.

“Yachimovich enjoyed the kind of backing that no other party leader has had in recent years,” Cabel said soon after the election last Tuesday. “We need to do some soul-searching and find where the mistake was.”

Senior party officials have grumbled that Yachimovich ran a one-woman show during the campaign, did not consult with anyone else on a strategy, and harmed Labor’s chances by focusing on socioeconomic issues to the exclusion of security and diplomacy.

Cabel is not expected to be the only one eyeing the top slot of the party. Labor’s No. 2 Isaac Herzog and former IDF chief of staff Gabi Ashkenazi, currently in a cooling-off period after leaving the army, are also being suggested as possible candidates for the job.

Senior party officials continue to talk of joining the coalition despite Yachimovich’s absolute rejection of the idea.

“If Netanyahu forms a true center government, with Likud, Lapid [Yesh Atid party], Hatnua, and Kadima, and asks us to join in order to advance the issues that are important to us, it will be hard to explain why we are sitting in the opposition,” Yedioth quoted a source in the party as saying. Those pushing to join the coalition intend to put the issue to the vote at a party meeting.

Before the elections Yachimovich vowed that she would not join a Likud-led coalition. However the success of the centrist Yesh Atid party, that won an unexpected 19 seats making it the second largest faction in the Knesset, has now altered coalition perceptions and configurations, opening the door for Labor.

Labor MK Nachman Shai said on Thursday that his party should consider the possibility of joining a Likud-led coalition. “On the eve of the elections, we said that we will sit in the opposition,” Shai told Israel Radio, “and that was an important statement… Now we need to… look around us and see what is happening.”

Outgoing MK Daniel Ben Simon, who had the No. 22 slot on the list and therefore will not retain his Knesset seat, told Israel Radio on Wednesday afternoon that because Yachimovich ran a “personal campaign,” she also was obligated to reach “personal conclusions” about the results and should step down from the party leadership.