Kemal Kilicdaroglu, head of the Republican People’s Party (CHP), told a televised meeting of business figures in Ankara that “not going to the ballot may have negative consequences.”
The CHP is campaigning for a No vote in the referendum, which would hand wide-ranging powers to President Recep Tayyip Erdogan, but Kilicdaroglu said the party would embrace both Yes and No voters after the poll.
“We are tired of fighting, the nation does not want fighting,” he said.
Kilicdaroglu added: “Either we will leave a happy and peaceful country following the referendum or we will leave an undemocratic public, which has been divided into two or three pieces.”
The referendum will see voters cast their ballots for or against an 18-article bill passed by parliament in January.
The reforms would abolish the post of prime minister and allow the president to retain ties to a political party.
If the electorate accepts the proposals, simultaneous parliamentary and presidential elections for five-year terms would be held in November 2019.