Liberal leader Justin Trudeau speaks during a campaign rally in Calgary, Alberta, Oct. 18, 2015. Reuters/Chris Wattie

Reuters -- Canada's federal election Monday could have a wide range of outcomes, some of which could lead to a period of prolonged uncertainty.

The three main parties are the Conservatives, led by Prime Minister Stephen Harper; the Liberals, led by Justin Trudeau; and the New Democratic Party (NDP), led by Thomas Mulcair. Smaller contenders include the Quebec separatist Bloc Quebecois and the Green Party.

Here are some of the scenarios that could unfold.

Majority Liberal Or Conservative Government

The most stable government is one where one party has a majority in the 338-seat House of Commons and therefore cannot be brought down by opposition parties. The Liberals have a shot at this if they can build on current polling around 36 percent to 38 percent. Parties usually need at least 39 percent, sometimes more, to win a majority. The Conservatives are polling closer to 30 percent. The NDP is likely out of competition in the low 20s.

Minority Liberal Government

A Liberal minority government would be reasonably straightforward since it can almost certainly count on support from the NDP for its broad program and for its budget, at least from vote to vote. It would be installed about two weeks after the Oct. 19 election. However, minority governments are typically short-lived, and Canada would likely face another election in six months to two years.

Strong Minority Conservative Government

It is possible the Conservatives will win the most seats even if they are behind somewhat in the polls, since they often perform a few percentage points better on election day. This is, however, the result that would be fraught with the most uncertainty, as the opposition parties have pledged to vote the government down at the first opportunity when the new Parliament meets.

If the Conservative minority is very strong -- at least 150 of the 170 seats needed for a majority -- it is conceivable that one or more of the opposition parties might somehow allow them to govern despite promises to bring Harper down, or that a handful of independents might provide the needed votes.

Weak Minority Conservative Government

Current polls predict this is more likely than a strong minority Conservative government. Harper says only the party with the most seats should form government, and smaller parties should not be allowed to displace it.

Some constitutional scholars disagree, but his position suggests that he will insist on laying out his government's proposed program at the so-called Speech from the Throne in Parliament. This would possibly be in late January and would mean his staying in power at least until then. Opposition parties can bring down the government in the vote on the Throne Speech.

If Minority Conservatives Fall At Throne Speech In Early 2016

If the opposition parties do team up to vote down a minority Conservative government, Gov. General David Johnston, Queen Elizabeth's representative in the commonwealth country, will decide whether to turn power over to one or more of the opposition parties, or to call a new election.

A government has never fallen on the Throne Speech federally, but it did happen in the province of Ontario in 1985. In that case, the two smaller parties reached a formal written agreement of support in exchange for enactment of specific policies. It is unclear whether Johnston would require a similar formal arrangement. This year, Trudeau rejected any formal arrangement with the NDP but has said he is prepared to work with other parties.

Coalition Government If Minority Conservatives Fall

If the Liberals and the NDP do vote down a minority Conservative government, there is a possibility that the Liberals and NDP could form a coalition, with cabinet ministers from both parties. It is remote, however, since Trudeau has repeatedly promised not to form a coalition.

New Election After Minority Conservatives Fall

If the Liberals and the NDP vote down a minority Conservative government, a new election in March or April 2016 is a possibility. This could happen if Johnston requires and fails to obtain a formal arrangement between the Liberals and the NDP in order to guarantee some stability.

NDP Government

There is always the possibility that the polls are completely wrong, as they have been in some recent provincial elections, and the left-of-center New Democrats will come out of nowhere and displace either the Conservatives or the Liberals, or both. If the polls are right, however, that is remote.