The corruption issue also has raised the question: In a region where graft is so entrenched, who will be left to govern if the swamp is fully drained?
“Across the region, polls consistently show that corruption is an increasingly salient concern,” said Michael Shifter, president of the Inter-American Dialogue, a Washington-based research group. “Yet many are also wondering if addressing underlying issues could risk paralyzing the economy or undermining governability, at least in the short term.”
Originally billed as the site of President Trump’s first Latin American visit, the summit’s focus shifted when the president dropped out amid rising tensions with Syria — and an F.B.I. raid on the offices of Mr. Trump’s personal attorney that has now become a White House crisis.
President Nicolás Maduro of Venezuela was barred from attending, and President Raúl Castro of Cuba decided not to go amid complaints of authoritarianism in coming presidential elections in both countries.
Mr. Trump’s absence has forced regional leaders instead to consider rising anger at the corrupt practices in their own countries.
The bribes from a single company alone have been enough to give the region pause.
Mr. Kuczynski is just one of the last four Peruvian presidents who is either under investigation or charged with corruption in a widening case involving Odebrecht, a Brazilian construction company. Ecuador’s vice president was sentenced to a jail term for receiving bribes related to the company. An ousted attorney general in Venezuela has released tapes saying that Mr. Maduro received $35 million in campaign contributions from Odebrecht in exchange for better treatment.
“Corruption undermines the public belief that democratic institutions work for them,” a major issue during the election year, said Mark L. Schneider, a former State Department official who now works at the Americas program of the Center for Strategic and International Studies in Washington.
On Thursday, the foreign ministers of the participating countries began negotiating the text of a document meant to be a blueprint for countries to fight graft within and between their borders.
The text was expected to include proposals for citizen watchdogs, protections for whistle-blowers and the press, more transparency in government contracts and the sharing of information by prosecutors.
“The summit has one substantive theme to deal with: democratic governance to confront corruption,” Néstor Popolizio, Peru’s foreign minister, told reporters this week.
Mexico, where voters pick a new president in July, has become a major focus of the corruption debate.
President Enrique Peña Nieto and his Institutional Revolutionary Party, the PRI, have been mired by scandals, starting with a revelation that his wife had bought a multimillion dollar home from a government contractor under favorable terms. More recently his government was found to have spied on journalists and human rights defenders and done little to investigate the surveillance abuses when exposed.
The front-runner in polls to succeed him is Andrés Manuel López Obrador, a nationalist whose anti-corruption rhetoric and pledge to govern austerely has struck a chord with voters.
In Colombia, scandals within one of its newest political groups have been creating election waves.
On Monday, Mr. Santos announced the arrest of Mr. Hernández, the blind former rebel who was one of the top leaders in the Common Alternative Revolutionary Party, which was formed by guerrilla fighters after they signed a peace deal in 2016.
The authorities said Mr. Hernández, whose group has renounced decades of violence and drug running, was in the process of trafficking 11 tons of cocaine to the United States — even as he prepared to take one of the party’s first congressional seats. The trafficking accusations immediately turned into a political football in the May election, where the front-runners harbor deep criticisms of the peace deal.
Some point out that bright spots exist in the region as well.
In Guatemala, high-level investigations of corruption have been outsourced to an independent body of international prosecutors backed by the United Nations. Working with the attorney general, they gathered evidence against Otto Pérez, who resigned as president in 2015 and is awaiting trial on corruption charges.
Two countries in the south, Uruguay and Chile, both scored well on Transparency International’s Corruption Perception Index in 2017, holding the 23rd and 26th places out of 180 countries. (The region’s largest countries sit in the middle, around the 100th slot.)
Mr. Schneider, the former State Department official, said Chile in particular had much to teach other countries when it came to fighting corruption.
For example, after family members of Michelle Bachelet, until recently Chile’s president, were implicated in a tax-evasion scheme, Ms. Bachelet appointed a council headed by an economist, Eduardo Engel, to propose reforms.
A number of new laws and institutions were created from his recommendations, which were embraced widely and continue into the presidency of Sebastián Piñera, a right-wing rival of Ms. Bachelet.
“Chile is as ideologically polarized as any country in the hemisphere, but they’ve adopted these measures, and kept them,” said Mr. Schneider.