Confused about what's at stake in Ukraine's elections? Here are five things to know.

Ukraine's presidential election this weekend is perhaps the biggest in the country's modern history, and will be closely watched all across Europe.

The presidential election that Ukraine aims to hold on Sunday will be the nation’s biggest test since it gained independence from Moscow 23 years ago. The outcome could determine whether modern Ukraine continues forward as a democratic nation, is irrevocably divided, or, in the worst scenario, descends into civil war.

The logistics of polling are hugely complicated for the interim government, which took power after the former president, Viktor Yanukovych, fled the country in February. He faced widespread protests against his rejection, under pressure from Russia, of a European trade and political agreement. But while his ouster was good news to Ukrainians in the country's west, it was viewed with suspicion in the east. There, many view the caretaker government as illegitimate, with pro-Russian armed separatists asserting authority in swaths of eastern Ukraine.

The election features 20-some candidates in the first round, scheduled for May 25. If no candidate gets an outright majority, a second round will follow on June 15. The clear frontrunner is Petro Poroshenko, a businessman also known as the “Chocolate King.” Trailing in a distant second is Yulia Tymoshenko, who emerged as a leader of the Orange Revolution but is marred by corruption scandals during her leadership.

The campaign has invoked the rhetoric common of any race. But with Ukraine's civil strife and the overarching confrontation between Russia and the West, this will be one of the most closely observed elections in European history.

Here are the five things to watch:

1. What's at stake for Ukraine?

The crisis that erupted in November in Ukraine has already redrawn the map of the nation, with Russia annexing Crimea in March following an independence referendum. Rebels in two regions of eastern Ukraine, Donetsk and Luhansk, subsequently held their own referendums this month and declared their independence from Ukraine, though without the sort of support, both within their regions and from Russia, that Crimea enjoyed.

Talks to bring the country together have made little progress. The divisions that have grown in the past six months – largely between pro-Europe leaders in Ukraine's west and more polarized pro-Russian forces in the east, even as Russia has appeared recently to back down –  threaten to unravel the national fabric, and many view this election as the only way forward to unify the nation. 

Despite the obstacles – in addition to the corruption and distrust that have marred Ukrainian democracy in the past two decades – some do believe that a successful election is the only way to steer the country away from crisis. “I think they… realize how dire the situation is,” says Steven Pifer, who was the American ambassador to Ukraine in the late 1990s. "And if they do not take advantage of the possibilities they have now they will be in a very difficult situation for years, if not decades."

2. What would undermine the elections?

A high voter turnout in an environment devoid of violent clashes or threat is the key to this election. Some 36 million Ukrainians are eligible to vote, and polls have placed turnout estimates at nearly 80 percent, including in eastern Ukraine. But in some parts there, armed separatists have threatened to prevent voters in the east from exercising their right to vote, so there is likely to be some violence and disruption no matter what. The question is at what scale.

“They key to elections being dubbed successful are higher voter turnout and relatively little violence, so that no one, whether inside Ukraine or outside, can say that they are illegitimate,” says Gwendolyn Sasse, a professorial fellow in politics at Nuffield College in Britain.  

3. What role does Russia play?

Russia looms large over the election.

At present, there is no sign they will directly intervene. The US and European Union have made May 25 into a red line with Russia, repeatedly threatening further sanctions on Moscow if it disrupts the vote in any way. Russian President Vladimir Putin has called for the vote to go forward, and this week he officially ordered troops to abandon military exercises along the Ukrainian border (though NATO says it has seen no signs of Russian withdrawal).

But if Putin comes out declaring the poll illegitimate for any reason, Ukraine might start at square one again – or worse. It is almost certain that independence seekers in the east will not recognize the vote, says Amanda Paul, an analyst at the European Policy Center in Brussels. “So Russia’s response will be important. If they recognize the elections as legitimate, I don’t think it will make that much difference what [separatists] would say in the east.”

4. If the election is a success, what’s next?

Although a successful election is considered vital to Ukraine’s future, it is just the beginning.

Most observers agree that for the state to have legitimacy, it needs a democratically elected president, a new parliament – the current one was voted in during Mr. Yanukovych’s tenure – and a new constitution that gives more recognition to Russian-speaking minorities in the country. A new constitution would also entail some form of decentralization that gives more autonomy to the regions, particularly in the east, which resents the firm grip Kiev has over regional matters.

A legitimate election can also lead to rapprochement with Russia: a key to Ukraine’s future. In the longer term, Ukraine's economic crisis, which will likely become more painful under the conditions the International Monetary Fund placed on it in return for loans, will test the political will of Ukrainians in the months and years to come.

5. Won’t we return to the status quo, just like after the Orange Revolution?

Ukraine also faced a pivotal moment after its Orange Revolution of 2004, when the country appeared to reject its pro-Russia government. But the new leaders that emerged from that movement were a disappointment both at home and abroad. Infighting and corruption hobbled any efforts to improve the quality of life of average Ukrainians, who ended up voting for the pro-Russian Mr. Yanukovych in the 2010 race. So observers are cautious about how reformist a new government will ultimately be.

But now, “Everything is different,” says Anders Aslund, Ukraine analyst at the Peterson Institute for International Economics in Washington. The aftermath of the Orange Revolution came with a sense of euphoria, in the context of a booming economy. This time, economically and politically the country is barely holding on. Because the situation is so dire, and so much is at stake, this might be the wake-up call that Ukraine didn’t have ten years prior.