Top Labor Party activists will convene in Tel Aviv on Thursday night for what is expected to be a turbulent political convention.The convention will be the first major event in the party since Labor leader Shelly Yacimovich led it to a disappointing 15 seats in the January 22 election and then refused overtures from Prime Minister Binyamin Netanyahu to join his coalition.Former ministers and MKs are expected to fiercely criticize Yacimovich at the event.Labor MK Eitan Cabel, who intends to run against Yacimovich for the Labor leadership, sent her a sharply worded letter Wednesday afternoon in which he accused her of trying to make undemocratic changes to the party constitution that would give her unprecedented power.“The constitution you are trying to pass would cast a shadow over Labor and make it into the Shelly Yacimovich Party,” Cabel wrote.“Instead of holding a necessary debate on the party’s failure in the election, you are trying to change the party’s bylaws to give yourself more power. This is nothing less than a dictatorial take-over using democratic means.”Cabel, a former Labor secretary-general, said he had never seen such an attempt to trample democratic values in the party. He compared Yacimovich’s tactics to those of former Labor leader Ehud Barak, who is despised in the party, and noted Yacimovich’s outcry when Barak tried to give himself additional powers.In the letter, which he sent to all 15 Labor MKs, he called for postponing the changes Yacimovich wants to make in the party constitution regarding how party institutions function.Yacimovich’s associates responded by noting that the Israel Democracy Institute had praised Labor for being Israel’s most active and democratic party. Sources close to Yacimovich said the party was never more undemocratic and inactive than the years Cabel ran it as secretary-general.Labor MK Erel Margalit, who ran against Yacimovich, called for the convention to deal with the results of the general election and not procedural matters. He vowed to draft the necessary number of Labor central committee members’ signatures to force a debate on the election.