Vice Premier Shimon Peres's official biographer, Dr. Michael Bar-Zohar, has entered the presidency race - apparently to put a spoke in the wheels of Labor Party MK Colette Avital's run for the post. In speaking with The Jerusalem Post on Tuesday, Bar-Zohar walked a fine line between stating that he was a serious candidate and pledging to step aside in favor of Peres (Kadima.) If Peres runs, "there is no chance [for a Labor party candidate], and that is what irritates me," Bar-Zohar said. "In truth, there are only two candidates: Shimon Peres and [Likud MK] Ruby Rivlin." The Labor Party can either throw its support behind Peres, or "it can appear as opposing Peres...giving [the presidency] to Ruby Rivlin," he added. While Peres himself has yet to announce his intention to formally replace President Moshe Katsav, whose term ends this summer, Bar-Zohar said he assumed that Peres would ultimately run. If not, Bar-Zohar said that he - as the author of more then 30 books (including Shimon Peres: The Biography), an academic, Knesset member from 1981-1984 and 1988-1992, one-time adviser to Moshe Dayan, and an envoy to the Council of Europe - was fully qualified to hold the post. Bar-Zohar said that if the vice premier sought the presidency, a Labor politician would act as a spoiler when the Knesset votes on the matter in May. He said that in that instance, left-leaning lawmakers would split their support between that candidate and Peres, thus handing majority support over to Rivlin, a former Knesset speaker. Bar-Zohar told the Post that if Labor supported his bid for the presidency, he would contemplate two options. "One is that I would turn to the leaders of the Labor party and suggest that we endorse Shimon Peres," said Bar-Zohar. If that failed, he said, he would remain in the race when the issue came to a vote in the Knesset in May, but withdraw before the second vote and instead "give [his] support to Shimon Peres." Other not wanting Rivlin to become president, Bar-Zohar said that he did not believe that Avital was up to the job. "The Labor party should not disgrace itself with a candidate who is not even worthy of being president," said Bar-Zohar, adding that his opinion was professional and not personal. Avital, he said, "is a very nice girl. We grew up together from the age of 14. She is a very nice woman, a good diplomat and good Knesset member." But the president, he said, must be someone of symbolic value to the nation. Sources close to Avital said they would not dignify Ben-Zohar's comments with a response. They attacked his tactics as underhanded and noted that Avital had the support of Labor chairman Amir Peretz and MKs Danny Yatom, Yuli Tamir and Ehud Barak, who is seeking to oust Peretz in the party primaries in May. But Labor MK Ami Ayalon, who is also running for party leadership, said he would support Peres in the Knesset vote. Bar-Zohar's decision to seek the presidency pushed Labor's central committee to delay its endorsement of a candidate. Instead, it decided on Monday to hand the matter over to the Labor faction for a decision to be ratified by the committee. No date has been set for the Labor faction meeting.