The book, written by a former adviser to Gul, exposes publicly for the first time the acrimonious and bitterly personal disputes between the co-founders of the ruling Islamic-rooted Justice and Development Party (AKP).
It was published just days after June 7 legislative elections where the AKP lost its majority for the first time since it came to power in 2002, triggering talk Gul is embarking on a campaign to replace Prime Minister Ahmet Davutoglu as AKP leader.
Gul was briefly premier when the AKP first came to power in 2002 and then served as foreign minister before becoming president in 2007.
He served his full term until August 2014 -- when Erdogan assumed the post -- and then slipped into the background.
While they are both pious Muslims, the more mild-mannered Gul contrasts with the increasingly divisive Erdogan, who has been further ruffled by the ruling party's loss of its majority in the polls.
-- 'Two acrobats can't be on same rope' --
The book, written by Ahmet Sever, a top advisor to Gul throughout his time in power, says that Gul wanted to return to frontline politics after he left the presidency.
But he did not for one simple reason -- Recep Tayyip Erdogan.
"Tayyip Bey would oppose it," Gul is quoted as saying in the book, using a typical Turkish form of address for Erdogan.
"It would cause a conflict between us. We cannot get on. It would not do the country any good either. Two acrobats cannot perform on the same rope," he says, according to the book "12 Years With Abdullah Gul".
The book recounts how Gul took a more moderate line over the anti-government protests of 2013 and says that Gul urged Erdogan late in that year to sack four ministers implicated in a corruption scandal but the Turkish strongman, then premier, resisted.
He was also bitterly critical of Turkey's aggressive diplomacy, telling Erdogan and Davutoglu, then foreign minister, they were acting like the foreign ministers of Egypt and Syria and harming Turkey's interests.
It claims to confirm an anecdote that Gul's wife Hayrunnisa warned at a reception to mark his departure she would launch an "intifada" against those who smeared her husband.
While commentators have seen the first "kiss n' tell" account of the AKP period in power as a goldmine, Erdogan loyalists have rubbished the book.
"I haven't read or looked at it. I don't think it is very important," scoffed Erdogan's son-in-law Berat Albayrak, who was elected an AKP lawmaker in the new parliament.
Others were less sanguine. "We see this as an attempt to throw a hand grenade at our party," said AKP lawmaker Samil Tayyar.
Sever said he had simply "written what I experienced", adding that Gul had told him to put publication off until after the election to avoid any impression of interference.
-- 'Normalisation of politics' --
Facing hostility from AKP hardliners, Gul denied that he had ordered the book to be written, saying while he was not enthusiastic about its publication he was always against any kind of censorship.
He warned against "making different calculations" out of the book.
But for all Gul's caution -- typical of a man who measures every word -- some anti-Erdogan commentators hailed the book's publication as a sign of an alternative within the AKP.
"I attach importance to Gul's entrance onto the stage in terms of the normalisation and democratisation of Turkish politics," Hasan Cemal wrote on the T24 website.
But Gul's habitual caution caused frustration, with many recalling how he earned the moniker "the notary" for rubber-stamping pro-Erdogan legislation during the final years of his presidency.
Rather than planning an immediate comeback, Gul, 64, may also be biding his time for the right moment after the AKP's loss of its majority dramatically reshuffled the cards in Turkish politics.
"If Gul returns to politics as premier, he will not allow anybody to interfere (in) his business," said Ozgur Altug at BGC Partners in Istanbul.
"But this does not mean that Gul is eager to return to politics. If needed, he can come back."
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