Shaken by a string of high-profile corruption scandals, Peruvians overwhelmingly approved a government overhaul that among other things sends all members of Congress packing by 2021.
Three of the four constitutional reforms proposed by President Martin Vizcarra were approved by nearly 80 percent of voters in a Sunday referendum.
Sick of a do-nothing Congress with leading legislators tainted by corruption and scandal, 78 percent of voters approved a measure banning consecutive re-election, according to official results with more than half of the vote counted.
That means that all 130 members of Peru's single-chamber legislature will be out of a job when their mandates end in July 2021.
Vizcarra harnessed public outrage to force Congress — controlled by supporters of Keiko Fujimori, Kuczynski's nemesis — to allow the referendum.
In late October Fujimori herself was taken into custody after a court ordered she be held in preventive detention for three years pending the outcome of a money laundering probe linked to Brazilian construction giant Odebrecht.
Peru's last four presidents — Alejandro Toledo, Alan Garcia, Ollanta Humala and Kuczynski — have all been linked to illicit Odebrecht payments.
Humala and his wife were briefly jailed, while authorities are seeking the extradition of Toledo, currently living in the United States and formally charged with taking a $20 million Odebrecht bribe.
Supporters of Fujimori, a two-time leading presidential candidate and daughter of jailed ex-president Alberto Fujimori (1990-2000), opposed the constitutional reform measures, as did supporters of Garcia and his once-powerful APRA party.
Voters jeered when Garcia — who was forced to abandon Uruguay's embassy one week ago when his political asylum request was rejected — cast his ballot on Sunday.