An opposition boycott has left President Pierre Nkurunziza as the sole candidate on the ballot as Burundians go to the polls Monday.

Weeks of tension and sporadic bouts of violence have been capped off by an unlikely calm as citizens vote for President Pierre Nkurunziza, who is certain to retain his office after Monday's election.

With the contest already won, Reuters has reported that many Burundians avoided the polls.

Despite the low turnout, there is a possible consolation for opposition candidates. Burundi's unique electoral system requires voters to place their choice into a white envelope while placing all others into a corresponding black envelope. Earlier this month, Burundi's electoral commission revealed it would treat any black envelope containing the president's ticket as a no-vote, essentially creating a referendum on Mr. Nkurunziza.

But that statement is unlikely to make up for the once bright outlook for the central African nation.

After May's municipal elections saw unprecedented voter turnout and a firm stamp of approval from international observers, many hoped that Burundi's summer long series of elections would be the final step in the countries long and tumultuous transition to democracy.  

But hopes quickly faded as the results were announced and President Nkurunziza's National Council for the Defense of Democracy party took over 60 percent of the available seats. Opposition parties, including main challenger the Forces of National Liberation, accused the electoral commission of fraud and pulled out of the presidential election.

But the chief observer of the European Union Election Observation Mission, Renate Weber, said there was no evidence of any such tampering during the municipal polls.

"In spite of errors, in spite of irregularities, generally the elections have been conducted in a manner that was indeed within the international standards. Why the opposition decided to withdraw?" asked Weber.

"They came with a number of allegations of fraud on the elections that we, personally through our observers but also through the observers of the civil society that were present, were not noticed. There is a difference between fraud and irregularities. Irregularities may be caused by human errors, by not enough logistics, not enough legal precision while fraud means an intention to affect the result of the election," said Weber.

Despite assurances of the international observers, Burundi has seen a surge in politically motivated violence in the time between polls.

Two weeks ago, a series of grenade attacks across the country injured over 20 people, and a fresh string of attacks on Tuesday killed one person and left another eight injured. The international community has also been targeted. On Sunday, a grenade went off near the offices of the European Union's observation team, though nobody was hurt.

The impact of the violence is now being felt outside of the small, central African nation. Burundi is the newest member of the East African Community, an economic and political union which is set to begin its formal integration process in July.

Kenya's foreign minister, Moses Wetang'ula warned that instability could jeopardize the country's status within the bloc.

"The gains in both security and stability that have been made in the last couple of years must not be lost. Having listened to all the parties, the region advises the people of Burundi, very firmly, that the region will not tolerate any slippage of the country into instability and violence," he said.  "We have impressed upon the remaining parties to participate fully in the remaining elections of parliament, senatorial and cell."

These are the first presidential elections since a 2005 peace agreement ended a 13-year civil war. Burundians will head to the polls again in July for two rounds of legislative elections followed by village elections in September.