Mercedes Aráoz had accepted the interim presidency from lawmakers, who tried to suspend President Martín Vizcarra for dissolving Congress. But in a win for Vizcarra, Aráoz resigned just a day later.
Martín Vizcarra called for new elections after dissolving Congress for blocking his anti-corruption efforts. But the lawmakers, who suspended him in turn, have no intention of going quietly.
The former police chief is among 14 people swept up in a raid and accused of buying infants of poor women. His partner, a well-known model in Peru, is considered the ringleader.
President Trump abruptly scrapped plans to attend a hemispheric summit meeting in South America this weekend. The White House says Vice President Pence will go in Trump's place.
Pedro Pablo Kuczynski, who has been accused of corruption, was hit with the release of video footage this week that appeared to support the allegations.
Peru's foreign minister says an invitation to the Summit of the Americas in Lima has been withdrawn over concerns the presidential elections in Venezuela will not be free and fair.