I rather think that the facts that Moghadam presents herself in passing undercut an argument that Marxists made an "error" in not allying themselves with liberals. Alliance is a two-way street, and liberals didn't love Marxists any more than Islamic populists did.
In any case, even if liberals and Marxists had been able overcome their mutual antipathy, there is still no evidence that together they could have overcome the Shah and establish an enduring government that served the working class, including women, _while defeating Islamic populists_. The balance of forces on the grounds pointed toward Khomeinists' hegemony to begin with, and, the (Muslim) Mojahedin's ill-considered uprising against the government when Iran was being invaded by Iraq (the invasion began on 22 September 1980), the uprising that most Iranians understandably did not support, and the Mojahedin's subsequent support for Saddam Hussein, more or less delivered the coup de grâce to not only itself but also the Marxist Left in Iran.
On 19 June 1981, the Mojahedin and Bani-Sadr called
upon the whole nation to take over the streets the next
day to express their opposition to the IRP 'monopolists'
who they claimed had carried out a secret _coup d'état_.
Their real intention -- never made explicit -- was to
duplicate the Islamic Revolution: first to incite a cycle of
ever-growing demonstrations; then to set off sympathy
strikes throughout the country, especially in the ministries
and factories; and finally to demoralize the armed might
of the state, in this case the pasdars, until the whole
regime crumbled. They also probably expected some
active support from their sympathizers in the armed
forces. Perhaps even the dispatch of military contingents
onto Tehran. Only the very first stage of this strategy was
accomplished.
. . . . . . . . . . . . . . . . . . . .
The June 1981 insurrection , , , failed. It failed in part
because the Islamic Republic, unlike the Pahlavi monarchy,
had many strengths; and in part because the Mojahedin,
despite their appeal, had their own weaknesses. . . .
Moreover, the Islamic Republic, with its charismatic leader
and populistic ideology, still enjoyed considerable support
among the general population, especially among the
traditional middle class, the bazaar lower class, and the
shanty-town poor. Unlike its predecessor, it had social
foundations.
The Islamic Republic could always undercut the opposition
by reminding the general public that the country was in the
midst of a life-and-death struggle with the Iraqi aggressors,
and that the imperialists, together with the 'reactionary
monarchists', were still plotting to undo the revolution. . . .
Whereas the Islamic Republic enjoyed these assets, the
Mojahedin suffered from a major liability. Their social
support, even though highly intense, committed and
enthusiastic, was confined predominantly to the ranks of
the young intelligentsia, especially the intelligentsia
born into the traditional middle class. The Mojahedin had
little support among the traditional middle class itself. They
had equally little support among the older generation of the
modern intelligentsia. They had a somewhat greater, but
still limited, following among the urban working class -- the
industrial workers and bazaar wage earners. And they had
almost no support among the rural masses, especially
among the landed and landless peasantry. Confined to the
intelligentsia, their 1981 insurrection was doomed to fail.
The only way they could have overcome this obstacle was
a military coup. But their support in the army was also very
limited. The failure of the Mojahedin was therefore
sociologically predetermined. (Ervand Abrahamian, The
Iranian Mojahedin, Yale University Press, 1989,
pp. 218, 259-260)
Khomeini was more popular than both Bazargan and Rajavi, the leader of the largest organization, which wasn't Marxist either, on the Left, and those who opposed Khomeinists did not have enough support in the most relevant sectors of society to overcome them. That was basically the single largest problem that neither Marxists nor liberals nor the Mojahedin could do much about. -- Yoshie