Left: Camila Vallejo speaks during a campaign rally in Santiago, Chile on Nov. 10, 2013 | Right: Kshama Sawant ran a grassroots campaign and said she ignored warnings that she had no chance of winning without corporate money or Democratic endorsement. Martin Bernetti/AFP/Getty Images (Left);Ted S. Warren/AP (Right)

Vallejo's pledge to "keep one foot in the streets" is a partial acknowledgement of the logic in the banner hung by the protesters at Bachelet's office — that winning elections will not, in itself, ensure far-reaching social change. And the compromises inevitably involved in operating in elected political office will leave both Bachelet and Vallejo vulnerable to outcries from the street.

Chile's leftists also have to contend with the traumatic memory of Salvador Allende, the democratically elected socialist who was overthrown and killed in a U.S.-backed coup in 1973, which saw thousands of leftists tortured and killed.

Melissa Sepulveda, the new head of the Universidad de Chile's student body, told Reuters before the election that she would not vote for Vallejo. "The possibility for change isn't in Congress," she said.

Vallejo's dilemma is this: Entering the system she fought so hard to change might compromise her credibility and also make it harder to keep people on the streets demanding change. At the same time, choosing not to participate in institutional politics might jeopardize her ability to forge change, critics say.

The left — at least in the somewhat centrist incarnation of Chile’s former President Michelle Bachelet — emerged dominant from last Sunday's first-round presidential election . But a sit-in at her campaign office that day by leftist students whose banner proclaimed that "Change is not in La Moneda (presidential palace), but in the streets" served up a reminder of the challenges of governing from the left in a situation where it has built up leverage in recent years through mass street protests. Bachelet, a socialist and a survivor of former dictator Augusto Pinochet's regime of torture in the 1970s and 80s, embraced some of the concerns of the protest movement, promising to help make higher education available to everyone by raising corporate taxes and rewriting the constitution. Among those elected to the legislature as part of Bachelet's New Majority coalition is Camila Vallejo, a former student leader who famously led thousands of Chileans into the streets in 2011 to demand educational reforms. Vallejo and three other newly elected legislators who all gained prominence as leaders of the Communist Youth of Chile vowed to use their platform in the legislature to narrow the gap between rich and poor, and counter pressure from Bachelet's right flank. But their entry into mainstream electoral politics has drawn criticism from their own left flank, among those who fear that being in government will demobilize their movement on the streets, and thereby dilute its leverage. Vallejo wasn't buying that argument, telling the Guardian the election to congress of student leaders "will not only demonstrate that the social movements can and should have their own representatives in congress, but also make it possible … to build political spaces that allow us to make the structural changes our society demands."

US activists elected

The dilemma faced by Chilean leftists may be recognizable to some in U.S. social movements, such as Occupy. Kshama Sawant, a former Occupy activist, was recently elected as a member of the Seattle City Council, after running as an avowed socialist. Upon beating Democratic Party incumbent Richard Conlin, she told Al Jazeera that it is important to enter the political arena to have a chance at actually changing policies, but, "in a genuine way" — something she said could be accomplished by "being independent of the two big-business parties."

Her politics, she said, would "give political voice to the struggles of low-paid workers, youth, people of color and all those who are shut out by the political machine that runs this city on behalf of the wealthy elite." Sawant sees the choice between life as an activist on the streets and "corporate politician" as a false dichotomy.

"People are forced to think you can either be an activist for the outside, or, if you’re in the inside, you cannot do what you want to do. But it depends on whether you’re clear that you cannot do it by being a part of the two-party system."

Sawant campaigned on raising the minimum wage to $15 and challenging social injustice in the corporate sector. She said she does not accept corporate funding, and paid for her campaign with donations from private individuals. She not only rejects politics as usual, but sees her role as disruption of the current order.

"What needs clarity is that Democrats (politicians) are not our allies either," she said, making the case for politics independent of the two-party system. Instead, she will seek a coalition of her own, using her position "to encourage more and more people to become part of social movements." And despite proclaiming an ideology that has long been marginalized on the U.S. political landscape, she hopes to capitalize on the growing number of young Americans who are said to think more favorably of socialism than capitalism, according to a 2011 Pew research poll.

"I can stay true to my principles but I am only one person," she said. "We need momentum."

Sawant, however, may not be quite so alone. In Cambridge, Mass., Nadeem Mazen, a former Occupy Boston activist, was elected to the City Council with a campaign focusing on affordable housing, education and social justice.

He believes the risks associated with trying to stay in office for decades might outweigh the benefits of long-term institutional politics. He promised to "cycle fresh voices" into the system, and imposed a limit on his term to stay "more focused." He used off-beat electoral techniques, such as employing video skills to bring politics closer to the public, which cannot always be expected to have time for "heavy reading to get up to speed on Cambridge politics," he said. He also promised to use at least a third of his city councilor salary to fund community organizing.

"I pledge to put my dollars towards hiring leaders and organizers in our community to proactively represent residents' interests," he said. Similarly, Sawant promised that if elected, "I will only take the average worker's wage and donate the rest to building social movements."

Having used credibility built through organizing protests to propel themselves into elected office, Vallejo, Sawant and Mazen — despite their ideological differences — share a common dilemma: How to maintain the leverage they built on the streets from inside political institutions long dominated by monied interests.

With wire services