What would have to happen in Parliament to trigger an early election?

MPs return Monday to a House of Commons that promises to be even more volatile than it was when they left it in June.

The end of the Liberal-NDP governance agreement makes an early election more likely but not inevitable.

A party can only continue governing as long as it has the «confidence» of the House — the support of a majority of MPs.

If a government loses an important vote, known as a «confidence» vote, it is deemed to have lost the confidence of the House. An election usually follows — although other parties can make a case to the Governor General that they have the confidence of the House and can govern. (The Liberals, NDP and Bloc prepared to make such a case in 2008.)

The confidence convention makes governing in a minority Parliament more difficult. The NDP had pledged to support the Liberals on confidence votes in exchange for movement on their policy priorities, but that support is no longer guaranteed.

Here's what would have to happen in Ottawa to trigger an early election.

Conventional confidence votes

Certain votes traditionally fall into the confidence category because they deal explicitly with the business of governing.

Votes on throne speeches, which outline a government's priorities at the beginning of a new session, are always considered confidence votes. The Liberals already have put forward a throne speech during this session; they'll only need to present a new one before the next election if they end the current session by proroguing Parliament.

Major finance bills — such as a budgets, supplementary estimates or fall economic statements that include new spending — are typically considered confidence votes.

Joe Clark's short-lived Progressive Conservative government lost a budget vote in December of 1979,