In the race for the White House, both Barack Obama and Mitt Romney have talked about sustainable development.
Yet the Green Party ticket, whose stance on the issue outpaces those of both the Republican and Democratic parties, is virtually unknown by the vast majority of US voters.
Romney, who has campaigned while standing in front of a coal mine in Ohio and enjoys support from the billionaire Koch brothers who made their fortune in oil, gas and chemicals, is the bane of many environmentalists.
Meanwhile, Obama has been criticized for not cracking down on hydraulic fracturing, or fracking, a technique that uses chemicals and water to blast through underground shale formations.
Obama, who has stated that "climate change is the one of the biggest issues of this generation" and promised to "begin to slow the rise of the oceans and heal the planet," has nevertheless given the green light for offshore oil leases in the environmentally sensitive Arctic Ocean, leaving the 66 percent of US citizens who favor tax breaks to curb greenhouse gas emissions without a candidate.
Six-time presidential candidate Ralph Nader blames the absence of awareness of the Green Party among most Americans on what he calls an "electoral system dominated by a two-party tyranny" and "a duopoly of the Republicans and Democrats."
"The Green Party not having a chance in this election is not because its proposals aren't supported by the majority of Americans," Nader told Al Jazeera. "Polls show their proposals like a living wage, cracking down on corporate crime, ending corporate bailouts, campaign finance reform, and many others, are what most people want. But since the two main parties are dialing for the same corporate dollars, they are the two heads of the corporate party, and this makes it nearly impossible for people to get on the ballot if they aren't in one of those parties."
A stacked deck
Dr. Joshua Tucker, a professor of politics at New York University, agrees with this assessment, and says structural factors of how the US electoral system runs can explain why the Green Party is largely absent.
"The system is geared to two parties," Tucker told Al Jazeera. "So it's practically impossible for a third-party candidate to be relevant in terms of having a chance of winning."
An example of the phenomenon comes from March 2012 polling carried out by Yale University and George Mason University. Polls found that 72 percent of Americans think global warming should be a priority for the president.
According to polling of registered voters, 84 percent of Democrats, 68 percent of independents and 52 percent of Republicans think global warming should be a priority.
But the Green Party ticket -- consisting of presidential candidate Jill Stein and running mate Cheri Honkala -- remains absent from the dominant discourse. The party was not invited to participate in the Obama-Romney presidential debates.
The majority of US voters are not even aware the Green Party is on the ticket for this election [GALLO/GETTY]
This is a surprising phenomenon, given the aforementioned polling data, along with the fact that both Republican and Democratic Party strategists have stated clearly that independent voters will decide the presidential race.
Dr. Tucker believes this is a continuation of a phenomenon that has been ongoing in the US for at least the last 40 years.
"You see someone hooking up with an already existing party, and they are usually a wealthy individual, like Ross Perot in 1992," Tucker said of the phenomenon. "Or you have someone with huge name recognition like Ralph Nader. But even guys like them have never received a single electoral vote."
Nader believes the system also silences third parties by keeping them out of the presidential debates. He has personally been barred from participating in presidential debates several times, even as a well-known democracy advocate and legitimate third-party candidate. The Commission on Presidential Debates requires candidates to receive 15 percent support in national polls before being allowed to participate.
"There is no other way to reach tens of millions of people other than with the debates," Nader said. "You can go all over the country as we did, and still only reach two percent of the people you can reach if you got on one debate."
Nader also describes a system that acts like a stacked deck, since on the state level it is extremely difficult to gain access to the ballot as a third party.
"We do not have a democracy for candidates that run on third-party tickets, because by the time they finish the battles just to get on the ballot it's Labor Day and they're exhausted and their finances are used up," explained Nader, who has experienced this several times personally in his presidential bids.
Of the biased structure of the current US political system, Nader added, "you are obstructing voters of a choice if you are obstructing the candidates from being allowed on the ballot."
By contrast, many western European countries have multiple parties on the ballots, instant run-off systems which allow voters to list their candidate preferences, and methods of encouraging candidates to get on the ballot.
"In the US you can have a secretary of state like Hillary Clinton who blocks parties from getting on the ballot," Nader said. "That's the dirty secret that she keeps under the carpet when she goes around lecturing foreign countries about democracy in the US. We have the least democratic electoral system in the western world."
Other political analysts, like Kings College of London Senior Research Fellow James Boys, who specializes in the study of the US system of government, believe the scale of the country is a factor that makes it challenging for smaller parties such as the Green Party to get national attention, primarily because of the prohibitively expensive nature of the advertising required.
"If you're a small group like the Greens, then you've got a real challenge just getting into the game," Boys told Al Jazeera.
Another issue, according to Boys, is how the Democratic Party has managed to convince much of the population that casting a ballot for the Green Party would be a "wasted vote," under the guise that the Democrats address many of the same issues as the Green Party.
"So you've got regional diversity, the cost of getting into the game, and the Democrats stealing funders of the Greens," Boys said, all of which explain why the Greens are largely absent from the dominant discourse around the current presidential election. "Then you've got various sectors of the country, like Texas, who would laugh a Green Party candidate out of the room," Boys added.
Not a Green future?
Despite the fact that the environment and climate change could be increasingly important issues in subsequent elections, Tucker is not optimistic about the Green Party ever having a chance of winning a US presidential vote.
"This is the norm," he says of the absence of a Green Party candidate in the national discourse this year. "You have third-party candidates that are basically irrelevant in US presidential elections. So the lack of a viable Green Party candidate in this election is not at all surprising."
Since the 1992 presidential campaign of Ross Perot, there has been a slow but steady call for a legitimate third party that can serve as both a challenger as well as an alternative to the Republicans and Democrats.
However, a recent Gallup poll suggests that there has been a continuing decline in support for a third party. While there are more than two dozen minor political parties in the US, support for a third party has dropped to 46 percent, and the minor parties, like the Green Party, enjoy only minor support and continue to be considered fringe.
Could this change?
Tucker doesn't believe so, due primarily to the fact that US electoral rules are not set up to accommodate a party that gets 7-8 percent of the vote.
"That gets you nothing in the US," he said. "You don't win a seat in the parliament like you would in a European country."
What might need to happen to change the system?
"You'd need full-scale electoral reform, which is not going to happen," he said. "Unless one of the major parties implodes, it's hard to imagine any situation where the Green Party becomes a major player in US presidential elections."
Nader's assessment is equally bleak.
"We have a Bush/Obama continuity in a foreign policy that is overwhelminging unconstitutional, so that's no choice for the voter," he exlained. "Pick your drone. Maybe the Republican's will color theirs silver and the Democrats will color theirs something else."
Al Jazeera asked Nader why he didn't run for president this election. "I've documented the futility and I don't want to pile more on top of it," he said. "We've documented the obstruction and injustice, but also the mindset of the voter has been trained from middle school to law school to accept the two-party duopoly and to either operate within it or stay home and not vote."
Perhaps an indication of low voter morale, the last three US presidential elections have only drawn between 50-57 percent of registered voters to the polls.
"Half of the people in the US are turned off and don't even want to vote," Nader says of this phenomenon. "In the US the two main parties can't even get 60 percent of the people to vote. That's how relevant they are."