He was also a part of Mr. Kuczynski’s first cabinet, becoming minister of transportation and communications, but was forced to resign after opposition lawmakers questioned his plans for a planned airport in Cusco, Peru’s most important tourist destination. After his resignation, he was appointed ambassador to Canada.
Even as Mr. Vizcarra was being summoned home from Ottawa, the scandal over Mr. Kuczynski continued to shake Peru. On Thursday, a Peruvian judge said he would consider a request to bar Mr. Kuczynski from leaving the country if the opposition-controlled Congress decided to accept the resignation, which would end his presidential immunity and make him vulnerable to prosecution.
Peru has a long history of presidents entangled in corruption scandals.
Alberto K. Fujimori diverted tens of millions in government funds in the 1990s to buy politicians and journalists, and until recently was imprisoned in Peru; Alejandro Toledo, was accused of receiving a $20 million bribe in the early 2000s from the construction giant Odebrecht; and Ollanta Humala and his wife were placed in pretrial detention over allegations of laundering $3 million in Odebrecht funds to support his 2011 presidential campaign.
It was Mr. Fujimori who, after complaining that Congress did not let him govern, helped establish the current political system. He sent tanks to shut down Parliament in 1992, and later blessed a Constitution that established a unicameral Parliament, doing away with the Senate.
“A system of government requires checks and balances, and we lost those with our current Constitution,” said César Landa, a constitutional lawyer. “Having a single chamber of Congress is not part of our democratic tradition.”
In 2016, Mr. Kuczynski narrowly defeated Mr. Fujimori’s daughter Keiko, but her right-wing party, the Popular Force, went on to dominate Congress. The president’s party won only a small minority.
“Mr. Kuczynski was politically isolated and a virtual hostage to the demands of Keiko Fujimori’s sector,” said Cynthia McClintock, a professor of political science at George Washington University.
Mr. Kuczynski’s weak government tested the limits of Peru’s fragile democratic institutions. During his 19 months in office, Congress either fired or forced the resignation of three ministers and at one point it fired the entire cabinet, and lawmakers tried to fire the attorney general and four judges of the Constitutional Court. Twice it accused Mr. Kuczynski of “permanent moral incapacity” and each time scheduled a vote to determine his fate.
“We are returning to a dictatorship, but this time from Congress,” Mercedes Aráoz, who had been Mr. Kuczynski’s prime minister, said this month.
Mr. Kuczynski’s enemies denied that Congress had overstepped its powers.
“I think we have strengthened democracy,” said Ursula Letona, a lawmaker with the Popular Force. “We haven’t broken the entire government — we’ve simply paved the way for an orderly and constitutional presidential transition.”
Whether Mr. Vizcarra will be given more room to govern is still an open question. “Personally, I’m very optimistic,” said Carlos Tubino, also a Popular Force congressman.
There are several proposals that would reinstate the Senate, which would make it harder for a single group to have as much legislative power. But they could face an uphill battle.
“The people don’t want two chambers of Congress because it means extra spending,” said Ms. Letona, who runs the congressional committee in charge of constitutional amendments. “And we are not a government branch that is particularly loved.”
Mr. Kuczynski’s political fortunes were closely associated with the Fujimori family.
He courted Mr. Fujimori’s son Kenji, a congressman openly at odds with his older sister Keiko. After Kenji Fujimori split with the Popular Force last December to create a faction that saved Mr. Kuczynski from impeachment, the president issued a medical pardon to Alberto Fujimori that allowed him to get out of prison. Mr. Kuczynski then brought Kenji Fujimori aboard the presidential plane, and took at least three lawmakers from the faction on trips.
When a second impeachment motion backed by the Popular Force threatened Mr. Kuczynski this month, he sought out Kenji for support. “No doubt he’s going to support me,” he told the local newspaper The Trome.
Then old-style Fujimori tactics seemed to emerge.
An ally of Keiko Fujimori’s sought meetings with Kenji Fujimori and his allies, claiming to be considering switching sides to back the president. He secretly recorded Mr. Fujimori and his aides bragging that those who supported Mr. Kuczynski reaped big rewards.
Ms. Fujimori’s party released the covert videos on Tuesday, dealing a final blow to Mr. Kuczynski and potentially ending her brother’s political aspirations. Congress is considering expelling Kenji Fujimori.
The arm-twisting and secret surveillance were reminiscent of the tactics used by Alberto Fujimori’s top adviser, Vladimiro Montesinos, a former spy chief who became infamous for filming hundreds of meetings where he handed out bribes, building pyramids of cash as he carried out negotiations. It was one of Mr. Montesinos’s videos that set off the downfall of Mr. Fujimori in 2000.
This month, Mr. Montesinos weighed in on the family fight. “In the 1990s, I used to speak more with Keiko Fujimori, not so much with Kenji,” Mr. Montesinos said on Facebook through his lawyer. “So, if I have left a mark on anyone, it’s on Keiko.”