In close elections like the one facing the United States this November, voter turnout is of paramount importance.

Four years ago, Barack Obama sailed to victory on a wave of unusually high electoral participation. Young people and African Americans, two groups whose levels of turnout tend to be lower than those of the general population, showed up at the ballot box in larger numbers than ever before. Their support was instrumental in Obama's historic victory.

Can he do it again? Enthusiasm is considerably lower this year, but the Democratic Party is hard at work energizing its base. Mitt Romney, the Republican contester, is doing the same.

Unfortunately for them, it's not easy to energize the American electorate. The United States has notoriously low voter turnout rates, so political candidates often have to fight tooth and nail to mobilize as many citizens as they can.

But what if they didn't have to fight? If every American were legally required to show up at the ballot box, perhaps the candidates could pursue their campaigns differently -- they could spend more time on the issues, and less time on negative ads that aim to dissuade voters from supporting the opponent.

Of course, forcing Americans to vote is easier said than done. Other countries have pulled off without a hitch -- but in the United States, any idea that includes the word 'compulsory' is sure to be hotly contested.

Looking Down Under

There are up to 32 countries around the world where voting is compulsory -- the specific number depends on how you define the word 'compulsory.'

Some countries, such as Australia, fine citizens who don't show up to the polls on voting day. Other countries, including Mexico, do not enforce their compulsory voting laws in any way. Still other countries have certain restrictions in place -- in Peru, for instance, voting is only compulsory for people under 70. And in many countries where casting a ballot is mandatory, voters still have the option to check the box for 'none of the above,' or even submit an empty ballot.

Along this scale, Australia stands as a good example of a country where voting is, for the most part, de facto compulsory. Citizens who do not register their attendance at a polling station are subject to fines, and those who don't pay are at risk of serving a minor sentence for jail time.

And since Australia is similar to the United States in terms of culture and overall wealth, it stands as the best counterpoint for comparison with the United States.

Down Under, eligible voter turnout for federal elections has exceeded 90 percent ever since 1925, when the law was first enforced. Polls show that the Australian public is satisfied with the compulsory system, with 70 to 80 percent approval ratings.

But Americans seem strongly opposed to the idea. The most recent major poll on record was conducted in 2004 by ABC News; it showed that 72 percent of those surveyed were against compulsory voting.

This is unsurprising for a country that highly values and freedom and personal responsibility. Still, proponents of compulsory voting argue that Americans would eventually come around. After all, they already participate in other mandatory activities including primary education and jury summonses.

But would it be worth it to mount a campaign for mandatory voting in the United States? It all depends on whether the country's relatively low voter turnout rate is cause for concern.

A Poor Showing

The Center for Voting and Democracy reports that American voter turnout "has never risen to levels of turnout in most of the well-established democracies in other nations.

"After rising sharply from 1948 to 1960, [U.S. voter] turnout declined in nearly every election until dropping to barely half of eligible voters in 1988. Since 1988, it has fluctuated, from a low of 52.6 percent of eligible voters in 1996 to a high of 61 percent of eligible voters in 2004, the highest level since 1968."

One recent report published by the International Institute for Democracy and Electoral Assistance puts the United States at No. 120 in a list of 169 countries ranked by voter turnout levels. Australia comes in first place, and virtually every other Western democracy has the United States squarely beat.

Would election results change if more people voted? Signs point to yes -- and here's where the argument gets political.

Studies have consistently shown that voters in the United States tend to be more affluent than non-voters. In addition, whites vote more frequently than non-whites, and older adults vote more frequently than the under-30 crowd.

And those Americans who don't vote -- they are generally poorer, younger and more ethnically diverse -- tend to lean liberal, according to a 2010 Pew Research Center survey.

The Pew researchers found that 54 percent of those who did not vote in 2010 mid-term elections self-identified as Democrats. Only 30 percent called themselves Republicans. It's no surprise, then, that advocates of mandatory voting tend to be liberal themselves whereas opponents are usually conservative.

The Deciding Vote

Making voting mandatory would do more than just tip the scales more in favor of liberal political candidates -- it could also change the course of political discourse entirely.

As long as turnout is low, it stands to reason that those who show up at the ballot box are more passionate about their convictions than those who don't. A politically moderate citizen may find it difficult to pick one side in a two-person race -- this gives them less incentive to vote.

And if moderates are inclined to stay out of the political discourse, our political system suffers.

William Galston, a senior fellow and domestic policy expert at the Brookings Institution, explained it this way in an op-ed last year:

"Our low turnout rate pushes American politics toward increased polarization. The reason is that hard-core partisans are more likely to dominate lower-turnout elections, while those who are less fervent about specific issues and less attached to political organizations tend not to participate at levels proportional to their share of the electorate."

When that happens, elected officials ascend to office under the mandate of a select group of citizens -- a group that tends to be more politically polarized than the general public. And the more polarized the government is, the more disillusioned moderates become -- in this way, decreasing turnout becomes part of a vicious cycle.

That's why Galston is one of the most vocal proponents of compulsory voting in the United States.

"Such a system would improve not only electoral politics but also the legislative process. Rather than focusing on symbolic gestures whose major purpose is to agitate partisans, Congress might actually roll up its sleeves and tackle the serious, complex issues it ignores."

This could go a long way toward solving the endemic problem of gridlock on Capitol Hill.

Mission Impossible?

Of course, arguing for change is one thing -- mounting a serious public campaign for mandatory voting is something else altogether. With public opinion decidedly against the notion, a serious national consideration of this issue seems a long way off.

For now, grassroots "Get Out the Vote" campaigns are working to address low voter turnout in the United States. These programs are implemented by a variety of organizations, most of which strive to be non-partisan even though it is generally understood that greater turnout will benefit liberal candidates in the end.

But those campaigns have been around for decades, and the United States still has one of the most dismal turnout rates among developed countries.

So maybe Australia has the right idea after all. Lisa Hill, a political professor at Australia's University of Adelaide, certainly thinks so. She has participated in compulsory voting for all her adult life, and in an op-ed last year, she outlined her experiences.

"Here in Australia, where we love freedom as much as anyone else, we have a mandatory voting regime that is well managed, corruption-free, easy to access, cheap to run and has an approval rating of more than 70 percent," she said.

She concedes that mandatory voting curtails personal freedom, but maintains that the compromise is well worth it.

"Democratic citizens owe it to each other to vote so that, together, they can constitute and perpetuate democracy and collectively enjoy the benefits of living in a properly functioning democratic society where everyone counts."