Karagiannis and McCauley have written an excellent article on the interesting alliance between the left and political Islam. It can be found here. A summary is below.

By Emmanuel Karagiannis, Ph.D. and Clark McCauley, Ph.D

It seems that the end of Cold War has brought an end to the enmity between communism and Islamism. Indeed, there are growing signs that an informal alliance is forming between political Islam and the radical Left, both at the state level and the level of groups and movements. Tehran has reached out to left-leaning regimes in Bolivia, Nicaragua and Ecuador, offering energy and trade. Europe’s Islamists and leftists have also joined forces. In March 2012, British firebrand socialist Galloway and his pro-Hamas Respect Party scored a sensational victory in Bradford West (a heavily Muslim-populated district) by-election, gaining 55,9 percent of the vote. Although this emerging alliance may appear as a tactical marriage of convenience between two fundamentally different political philosophies opposing the West, Reds and Greens have more in common than they dare to admit.
First, Islam and communism emphasize group goals over individual interests. Both seek to establish a society based on sacred texts: the Quran for the Islamists and the works of Marx and Lenin for leftists. Furthermore, they offer a vision of a just society that can be created on earth: the Marxist utopia of a classless communist society parallels the utopian vision of a restored Caliphate. Both claim to represent an absolute truth that would lead to the salvation of mankind. Both have an eschatological view of history that includes the inevitability of a final battle between good (socialist progress / Dar al-Islam) and evil (capitalist reaction / Dar al-Harb), and both can justify violence to achieve this goal.
Islamists and leftists have been keen to present themselves as part of the wider anti-globalization movement. A common denominator of the anti-globalization movement is its claim that big capitalism is inherently unjust in serving the interests of Western elites to the detriment of (working and Muslim) masses around the world. It is hardly a coincidence that Hezbollah’s new manifesto, published in December 2009, spends a great deal of time attacking “an economic system that only views the world as markets that have to abide by America’s own view”. Also, leftist groups have championed the cause of anti-globalization as the preferred form of anti-imperialism. The rationale has changed but leftists’ enemies are the same.
Moreover, both Islamists and leftists have portrayed the United States as the foremost imperialist power. This kind of framing resonates well for both, but for different reasons. For leftists, the U.S. involvement in the greater Middle East is outright imperialism the way Lenin described it. For the Islamists, American wars in the Middle East are just another episode in a long line of Western interventions to grab resources and land from the ummah. It is not rare to see pro-Hezbollah banners and posters of Nasrallah in leftist demonstrations in European cities.
Opposition to Israel has been another common obsession for Islamists and leftists. What brings together Islamists and leftists is deep hate for what, in their eyes, Israel represents. From the Islamist point of view, the establishment of the Jewish State was orchestrated by the Christian West to steal Muslim land in a repetition of the Crusades. For leftists, Israel must be fought as Washington’s colonialist ally in the Middle East. Recognizing Israel as the keystone of the Red-Green alliance, Iran’s President Ahmadinejaz has made the Palestinian issue his ideological core. He knows that for the radical Left, from Latin America to Europe and North Korea, the Palestinians are the new Cubans—the new Vietnamese who need international solidarity. By extension, befriending Iran is a logical thing to do for anyone who supports the Palestinian cause. Much to Tehran’s delight, Venezuela and Bolivia suspended diplomatic ties with Israel following the Gaza crisis in 2009, as did Nicaragua in response to the Gaza flotilla raid in June 2010.
No matter how unlikely it may seem, leftists and Islamists have come closer in recent years. Despite a long history of animosity and conflict, the two sides have joined efforts to confront the United States, Israel, and the West. Antiglobalization, anti-American and anti-Israel sentiments have provided a common framework justifying joint action for the sake of working and Muslim masses.