It is always exciting when a political party that seems to have been in power forever gets the boot. This could happen in Mexico tomorrow.
And it could be a Mexican with Irish blood that does it. Vicente Fox, the 6 ft 6 in swashbuckling "Marlboro Man" candidate of the National Action Party (PAN) may bring to an end 71 years of rule by the Institutional Revolutionary Party (PRI), whose banner is being carried by Francisco Labastida. His giant picture looms in front of my hotel room window accompanied by the slogan: "Let power serve the people."
It is one of those slogans that mean nothing, but the smaller letters, PRI, under Labastida mean an awful lot in Mexico, where that party has been identified with the state since it grew out of the violent revolution of 1910. A bit like Gaullism and early Fianna Fail, the PRI is a movement rather than a party and has the same colours as the national flag.
It has run Mexico since 1929 with PRI presidents being handpicked by their predecessors and ensured of re-election. The Peruvian novelist, Mario Vargas Llosa, called it the "Perfect Dictatorship" - the people voted but the same party always won.
Fox could end it tomorrow but it will not be easy. He and Labastida are about level in the opinion polls at 40 per cent but there is a third candidate, the lugubrious Cuauhtemoc Cardenas, of the left-wing Party of the Democratic Revolution (PRD), who could be the spoiler for Fox by splitting the anti-PRI vote.
This is the third time Cardenas, whose father was a revered president in the 1930s, has run for the top office. In 1988, it is generally accepted that he was cheated of victory by the PRI's Carlos Salinas when computers counting the votes mysteriously crashed.
Fox has done his best to persuade Cardenas to stand down to ensure an end to PRI's stranglehold on the presidency but with no success. Now they are exchanging insults.
Fox, who will be 58 tomorrow, has been stumping through the country in his cowboy boots, promising to modernise Mexico by breaking the PRI hold on the rigid economic structures. With his background in marketing Coca Cola and involvement in the family vegetable and fruit ranch, Fox appeals to the young entrepreneurial class.
He wants to privatise more of the nationalised industries, such as Pemex oil, and bring in more foreign investment. A few years ago, as Governor of Guanajuato state, he led a trade mission to get more investment for an area that already has large Kerry Co-Op and Smurfit operations.
Educated by the Jesuits and a practising Catholic, Fox is divorced and has four adopted children. His daughter Cristina campaigns with him and could be his First Lady, he says, if he wins Los Pinos, the Mexican White House. He is also anti-abortion, which worries feminists.
Labastida calls Fox "a question mark in boots" for his inconsistencies. Thus Fox has been critical of the Catholic hierarchy and likened the authoritarian bishops to the PRI while he has held up a statue of the Virgin of Guadelupe at election rallies. He has both praised and denounced banks, depending on his audience. He rashly said he could solve the peasant rebellion in Chiapas "in 15 minutes".
Fox has shocked some by his earthy language and has implied that "shorty" Labastida is gay and a cross-dresser, although the PRI former minister is on a second marriage and has had a daughter out of wedlock.
Labastida, after a shaky start when he tried to promote a "new PRI", is now probably the favourite. He turned for help to the party old guard, or "dinosaurs", who know every trick in the book when it comes to winning or buying votes. There are 59 million on the electoral list.
The independent Federal Electoral Institute (IFE) has spent $1 billion to ensure a fair election and counting of votes tomorrow and there will be a small army of international observers, including former President Jimmy Carter, to monitor the voting. But the IFE can do little about what has been going on during the campaign, as the PRI used its well-practised methods of handouts in rural areas.
The worst scenario for Mexico would be if Fox is narrowly defeated. He has backed off his threat not to accept the result if he is defeated by less than 10 per cent but a defeat by 1 or 2 per cent would certainly result in widespread claims of PRI skulduggery. Economic uncertainty and pressure on the peso could follow.
A narrow defeat for Fox, according to a former Mexican ambassador to Ireland, Agustin Gutierrez, would lead to widespread cynicism and possibly outbreaks of violence in Chiapas and among already rebellious students.
But would a defeat for Labastida be even more perilous for a Mexico so dominated by the PRI and with so many jobs and sinecures depending on party bosses? That remains to be seen but the party's grip on power has been gradually loosened in the past decade. And the economy has boomed after the chaotic collapse of the peso in 1994.
In 1997, the PRI lost its majority in the Congress lower house and the office of Mayor of Mexico City, the biggest in the world. Where it once held the governorship of all 31 states, the PRI now holds only 22.
The country's biggest problem is probably drug-related crime and kidnappings. But none of the candidates offers a convincing solution to clean up that blight on a country with so much promise.