FOR months before elections, Latin Americans are bombarded by campaign publicity. In Brazil an obligatory nightly hour of political broadcasts sees a succession of attention-seeking pledges from presidential candidates and local hopefuls. In Peru walls and even mountain boulders are painted with the names of candidates. Although social media are increasingly important, many of the region’s politicians still line the streets with posters and hold rallies, plying supporters with food, T-shirts and even cash.

Who pays for all the paraphernalia of electoral democracy, and what might they get in return? Revelations of corrupt political donations in several Latin American countries by Odebrecht and other Brazilian construction firms are sparking demands to tighten the rules on campaign finance. Nadine Heredia, the wife of Peru’s former president, Ollanta Humala, denies having received a $3m donation from Odebrecht for her husband’s victorious campaign in 2011. A former Colombian senator who admitted pocketing an Odebrecht bribe claims, without proof, that $1m went to President Juan Manuel Santos’s campaign in 2014.

Popular wisdom holds that Latin American elections are an increasingly expensive free-for-all. (Despite the free television time, the cost of Brazil’s campaigns may be similar to that in the United States, by some estimates.)

In fact, the region’s governments have long sought to regulate campaign finance, but often ineffectually, as Kevin Casas-Zamora, a former vice-president of Costa Rica, and Daniel Zovatto, an Argentine political scientist, point out in a recent survey of the issue. Whatever the rules, the reality is that a small coterie of private businesses stumps up most of the campaign cash almost everywhere, except perhaps in Uruguay and Costa Rica.

Uruguay was the first country in the world to give a public subsidy to political parties, in 1928. Now most Latin American democracies do so, but the subsidies are mostly small. In Venezuela, in theory, there are no subsidies; in practice the ruling party deploys unlimited state money and resources in its campaigns. All of Latin America except El Salvador bans foreign political donations. That did not stop Venezuela’s Hugo Chávez and Brazil’s Workers’ Party (via Odebrecht) from financing campaigns in other countries, to counter the centre-right bias of private donations.

Corporate donations have sometimes led to the private capture of slices of government. Take Chile, one of the region’s more advanced democracies, which has recently been shaken by several political-financing scandals. The most worrying involved revelations that several big fishing companies financed politicians who should have regulated them, but instead allowed them unrestricted rights to plunder Chile’s depleted seas in perpetuity.

Chile’s parliament has approved new rules drawn up by a committee headed by Eduardo Engel, an economist. They restrict outdoor advertising, increase public subsidies, bar corporate donations and regulate those from individuals. Similarly, Brazil has banned corporate donations and shortened the duration of the official campaign. Several other countries are considering tighter rules. But in Chile some politicians blamed the record-low turnout (of 35%) in municipal elections last October on the lack of a “campaign atmosphere”. In Brazil’s municipal vote last year, the campaign curbs seemed to have helped more incumbent mayors than expected win re-election.

Campaign-finance reform is fraught with such trade-offs and unintended consequences. Public financing of politics is unpopular; in Mexico it may have raised, rather than cut, the cost of campaigns. Bans on corporate donations (which exist in several countries) risk prompting recourse to organised crime for money.

Nevertheless, the status quo has become untenable. It seems right to try to cut the cost of campaigns by shortening them. As for corporate money, some would argue for obligatory disclosure rather than a ban. Mr Engel says a role for corporate money might be acceptable in Chile in the future. Perhaps most important is that enforcing either transparency or bans requires capable and neutral electoral authorities. In Chile’s municipal campaign, the authority absurdly made it hard for individuals to display campaign posters in their homes.

In a region of great inequality of wealth, it is hard to disagree that corporate political donations should be tightly regulated. But campaign finance is a problem for which there are no panaceas, only hard choices and one incontrovertible truth: democratic politics costs money, and someone has to pay for it.