With the turn of the calendar to 2015, Canadians entered a federal election year. While the date is fixed for later this fall, speculation that Prime Minister Stephen Harper could pull the plug early has ramped up in recent weeks.

The election is scheduled for October 19, but Harper could send voters to the polls before then, if he wants to avoid some key issues that could be a drag on his next campaign.

Here are four reasons why Canadians could be called to the polls early.

The economy

Plummeting oil prices are threatening to seriously dent the budgets of the federal and a number of provincial governments, and Harper may want to make his case to voters while the economy remains relatively stable.

CIBC economists warned in a recent report that various levels of government in Canada stand to lose a combined $13 billion in revenue on falling oil prices, even if the price of oil rebounds to $70 per barrel. The federal government alone would see $5 billion disappear from the books, the report said.

Earlier this week, the Conference Board of Canada turned up the heat, predicting that Alberta will “very likely” go into recession, even if oil prices rebound to US$65 per barrel, and drag other regions of the country down with it.

Security scares

In the wake of last year's attack on Parliament Hill, and the international security challenges posed by Islamist extremists as seen most recently in the deadly Paris attacks, Harper may want to ask voters to extend his mandate as guardian of national security now, rather than risk the uncertainty of a new government and its untested approach later in the year.

Mike Duffy

The Senate expenses scandal left the government in defence mode for months, governing in the shadow of RCMP investigations and external audits.

The first senator to be charged in the scandal, Mike Duffy, goes to trial in April and the legal proceedings are sure to make headlines that the prime minister might not want to deal with on the campaign trail. Rather than await the undertain outcome of the trial, and hope Canadians forget before heading to the polls, the prime minister could opt to try and get voters out beforehand, instead.

Justin Trudeau

The Liberals shot up in the polls following the election of Justin Trudeau as leader a year ago, and have stayed there ever since.

Harper and the Conservatives have hammered Trudeau over his political inexperience and attack ads have focused on his fitness to govern. While the Liberal leader has been relatively unscathed by the attacks, bringing the Liberals back from the near-dead, and luring a slate of high-profile candidates to run in the next election, waiting could give Trudeau more time to not only build his war chest, but raise his profile with Canadians too. By calling an election sooner rather than later, Harper's Conservatives could capitalize on their funding advantage, instead.

But some experts say…

While there are compelling reasons for the prime minister to pull the trigger on a spring election campaign, some say that remains unlikely.

CTV’s Ottawa Bureau Chief Robert Fife said Wednesday that sources close to Harper insist the election date remains Oct. 19.

And Scott Reid, former communications director for prime minister Paul Martin, said that, if oil prices continue to compromise Canada’s economic conditions, Harper may want to delay an election.

But for now, everything is just speculation, as Fife pointed out in an interview on CTV's Canada AM.

“A week is a lifetime in politics,” he said. “So who knows?”