Kuczynskis administration was plunged into crisis this week when Popular Force presented videos that appear to show allies of the president including Keikos brother, Kenji Fujimori trying to buy the vote of lawmaker Moises Mamani ahead of Thursdays congressional debate on impeachment.
Kuczynski, a 79-year-old former Wall Street banker who once held United States citizenship, promised a "constitutional and orderly" transition of power to end what he described as a hostile political climate that had made governing almost impossible.
The professor said that besides his alleged links to Odebrecht, Kuczynski's fall was mainly due to the pardon he gave former president Alberto Fujimori in December for humanitarian reasons.
OTIS: All this prompted Peru's Congress to try to impeach Kuczynski in December.
"Confronted by this hard situation in which they have unjustly made me appear culpable of things in which I didn't participate, I think it's best that I resign the presidency", Kuczynski said.
"I don't want to be an obstacle blocking our nation from finding the path to unity and harmony that it so much needs and which I was denied", he said, adding that the campaign in favor of his removal had caused "enormous damage" to Peru's democracy.
Defying Peru's ban, Maduro has vowed to be at the mid-April Summit of the Americas, which his biggest worldwide critic - U.S. President Donald Trump - is also due to attend.
Even some of his staunchest defenders called for him to step down, although opposition lawmakers signaled they might not accept his resignation.
Popular Force is led by Keiko Fujimori, daughter of disgraced former President Alberto Fujimori and Kuczynskis rival in the 2016 election.
But he resigned on Wednesday in the face of near-certain impeachment over a graft investigation into his connections to Odebrecht, a Brazilian construction company that has acknowledged bribing officials across Latin America. He had been facing an impeachment vote on Thursday. Vice President Martin Vizcarra, now the ambassador to Canada, could be sworn in on Friday.
"This government thought it could buy everything".
On Sunday, Kuczynski said removing him would amount to a "coup d'etat" in the South American country - and tarnish Peru's image just before it is due to host the Summit of the Americas.
The pardon came 3 days after Kuczynski narrowly escaped impeachment over a corruption allegation.
Kuczynski said during the week he was confident of defeating the impeachment vote.
Odebrecht has admitted spending millions to bribe government officials across Latin America to secure public works contracts.
Odebrecht said it paid five million dollars in fees to companies linked to Kuczynski when he was Peru's economy minister, under Toledo.