Greek Prime Minister Antonis Samaras formally requested the dissolution of parliament on Tuesday, marking the start of a monthlong election period that the government has already started to frame as a referendum on Greece’s future in the eurozone.

In a meeting with Greek President Karolos Papoulias, Mr. Samaras obliquely blamed the opposition Syriza party for blocking this month’s parliamentary procedure to elect a new head of state. Parliament’s failure to elect a new president in a third and final vote this week has forced Greece to hold early national elections. The elections are scheduled to be held on Jan. 25, some 18 months ahead of schedule.

“When it comes to the security and stability of our nation, then you understand that a battle for truth and responsibility is needed,” said Mr. Samaras. “With the country’s presence in Europe depending on this battle, you understand that we will approach it with a sense of responsibility for the future of our children.”

Later Tuesday, Greece was expected to appoint caretaker ministers to the interior and justice portfolios to oversee the elections process–an electoral formality–along with a new government spokesman.

The dissolution of parliament actually takes place when a presidential decree is signed and is posted on the doors of the parliament’s two main entrances in central Athens.

While that is not expected to happen until Wednesday, Greece’s election campaign was already under way on Tuesday.

Earlier in the day, the newly formed, centrist To Potami party, officially presented its campaign positions at a public gathering, while socialist party leader Evangelos Venizelos–deputy head of Greece’s two-party coalition government–called a meeting of his party’s electoral committee.

Two and a half years ago, at the depth of its debt crisis and with the country’s future inside the euro in doubt, Mr. Samaras’s New Democracy party waged a bitter campaign against Syriza, warning that its anti-economic reform policies would spell the end of Greece’s euro membership. As bank depositors withdrew billions of euros from Greek banks and private companies cut their commercial links to Greece, the fear tactic worked: New Democracy edged past Syriza by about 170,000 votes, winning elections in June 2012.

Nowadays, those fears have receded and Greece is no longer in such desperate need of cash handouts from its eurozone-led EUR240 billion ($292 billion) bailout package. But many investors still remain concerned about Syriza’s policies–and a potential clash with Greece’s creditors–should it win next month’s elections.

In the past month, the Athens stock exchange has lost roughly 15% of its value amid fears of the political uncertainty–and a possible Syriza win–ahead. In a research note on Tuesday, ratings agency Fitch warned that the political uncertainty could lead to renewed capital outflows from Greece and a strain on government cash reserves.

Though Syriza dismisses such fear-mongering, party leader Alexis Tsipras moved to reassure Greeks that their bank deposits were safe.

“The systemic banks have gone through crash tests. The consolidation of banks has moved ahead. The four systemic banks are part of the European banking system. The balance of the banking system is something that concerns all of us,” Mr. Tsipras said in a speech late Monday.

In the latest poll, conducted by pollsters Marc on behalf of private television station Alpha before the announcement of the snap elections and released on Monday, 28.1% of those questioned said they will vote for Syriza and 25.1% for New Democracy. The 3% lead for Syriza has shrunk from 3.5% in a previous poll held a week earlier.

It remains unclear whether either party will garner enough popular support to rule on its own, or be forced into a coalition government, something that is further stoking fears of an extended period of political uncertainty ahead.