In most democracies, however, an election can happen at any time, as the government is dependant of parliamentary arithmetic. The head of government (typically the prime minister, or in Ireland, the taoiseach) is elected by a majority of the lower house (in Ireland, the Dáil).

The government then has four to five years in which to rule. It's deemed a "minority" government if it relies on the support of parties and/or individuals who are not part of the administration. Sometimes that can be a manageable situation, but at other times it can lead to governmental instability, as happened after the 1981 election in Ireland. There were two more general elections in 1982 before a stable coalition government was formed.

A government defeated in a key parliamentary vote can be left with no choice but to "go to the country." But generally speaking, a prime minister can within certain limits control precisely when an administration seeks to renew its popular mandate. Indeed, it's one of the valued powers available to a country's top politician and is considered part of the art of politics.

Eamon de Valera was elected prime minister for the first time in 1932, forming a minority government with Labor Party backing. In 1933, he called a "snap" general election and obtained a Fianna Fail majority for the first time. Unhappy with his 1937 general election mandate, he called another snap election in 1938. The pattern was repeated in 1943 and 1944.

Many countries restrict parliamentary terms to a maximum of five years. (Ireland's constitution allows seven years, but also says that can be reduced by law. And it has been -- no Dáil can sit a day more than five years.) It's long been considered prudent, however, for a government to seek a new mandate after four years.

In 1976, James Callaghan succeeded Harold Wilson as British prime minister, and by 1978 the Labor government had been in power for four years. Some historians and commentators have argued that had Callaghan gone to the country in the fall, he might have been returned to power. Instead, he waited, calling the election in May 1979, and was soundly defeated by Margaret Thatcher.

In most systems, the prime minister must formally seek permission from the head of state to dissolve parliament.

When it was suggested in 1994 -- while Albert Reynolds's government was imploding before midterm -- that President Mary Robinson might refuse to dissolve the Dail, it concentrated people's minds. Labor, the minority partner in government, broke with Fianna Fail and formed a new government with Fine Gael and Democratic Left. It was the only time in Ireland's history that a new government was formed without an election taking place.

In 1997, Bertie Ahern was elected taoiseach with the support of the Progressive Democrats, his new partner in government, and four independents. (In some ways, it was like an old-style Fianna Fail majority government as both the PDs and the independents had their roots in the Fianna Fail family.) Though technically a minority government, it made a virtue of it, saying it alone could provide stable rule, and it lasted longer than any since Irish independence.

If the current Fianna Fail/PD government was to repeat that experience, it would rule until 2007. Although 2006 is a far more likely date.

But Ahern might consider the autumn an opportune time for a snap election. The electorate has registered its protest in the combined local-European elections, but might take a different view in a general election. Fine Gael has bounced back from a supposed irreversible decline, and this has made its uncharismatic leader, Enda Kenny, the likely alternative taoiseach, rather than the more dynamic Pat Rabbitte of the Labor Party. And Ahern might also calculate that if the government went for a four-year term, the electorate would balk at a third consecutive Fianna Fail-led government. Fianna Fail people talk now of rebuilding their party over the next two years ahead of a general election. But it's just as likely that the government could look increasingly tired over time, and then Ahern might face an internal challenge.

Having received good news on economic growth and having presided over the expansion of the EU, the taoiseach might feel that he might not get a better opportunity to accentuate the positive.