Peruvian interim President Francisco Sagasti talks to the media in Lima, Peru, Nov. 19.

Photo: sebastian castaneda/Reuters

Millions of Peruvians have lifted themselves out of poverty in the past two decades, thanks to a more open and market-oriented economy yielding fast growth. Socialists don’t like it. But they have been unable to reverse the laws underpinning the country’s progress. Now they’re using the latest political crisis to make another try.

Peru’s rampant corruption is again on the front burner. Coming amid the Covid-19 pandemic and a deep recession, it has raised the ire of the nation.

Yet it’s hard to see how an electorate that so often votes for populism at the polls can extricate itself from the grasp of crooked politicians. The hard left’s solution, which is to rewrite the 1993 constitution and give the state a larger role in the economy, would make things worse.

Francisco Sagasti was sworn in as interim president Tuesday. The center-left former lawmaker replaces interim President Manuel Merino, who only a week earlier had replaced President Martín Vizcarra, who in 2018 replaced President Pedro Pablo Kuczynski, who resigned amid allegations of corruption. With me so far?

The civilian government has mostly followed the law, the line of succession has been more or less respected, and an April election for a new president is on schedule. That’s the good news. But it’s been a bumpy ride.

Mr. Vizcarra had no vice president when he was impeached by a 105-19 vote in the unicameral legislature earlier this month. As the head of Congress, Mr. Merino was next in the line for the job. But Peruvians who didn’t approve of the impeachment took to the streets in protest. Two people died in violent clashes with police. In an effort to restore calm, Mr. Merino agreed to step aside and let Congress choose a caretaker president.

Hard-left lawmaker Rocío Silva-Santisteban ran for the post unopposed, but she couldn’t garner enough support from her peers to win when her candidacy was put to a vote. A day later Mr. Sagasti—of the moderate Purple Party, which had opposed Mr. Vizcarra’s removal—won congressional approval. The streets are calm—for now.

Vizcarra supporters say he is a victim of congressional abuse of power. But he may have made his own bed in September 2019 when he unilaterally dissolved Congress.

The constitution allows a president to send legislators home and schedule new elections if they give him two votes of no confidence. One had already occurred. Then, on Sept. 30, 2019, Congress named a new Constitutional Court justice—which is its prerogative—ahead of considering a judicial reform he had proposed. Piqued by the move, Mr. Vizcarra declared it a “de facto” second vote of no confidence even though no such vote had occurred. Scholars are still debating the legality of that decision, though the high court voted 4-3 in the president’s favor in January.

Mr. Vizcarra ruled by decree for five months. His relationship with the new Congress elected in January wasn’t much better. In September lawmakers released audiotapes that allegedly exposed witness tampering on the part of the president, but a subsequent impeachment vote failed.

After whistleblowers came forward alleging Mr. Vizcarra took bribes while he was governor of the Moquegua region from 2011-14, a second vote to impeach succeeded.

Technically Mr. Vizcarra was removed on grounds of “moral incapacity,” the same tool used to impeach President Alberto Fujimori in 2000. Mr. Vizcarra is crying foul because he has not been convicted of a crime. But impeachment in Peru is a political process, as it is in the U.S. and most other countries. Even the high court, which leans in Mr. Vizcarra’s favor, ruled last week that his removal is constitutional.

Plus, as a self-described champion of anticorruption, Mr. Vizcarra needed to be squeaky clean. A judge has barred him from leaving the country and prosecutors have charged him with aggravated collusion, bribery and illicit association to commit a crime. Mr. Vizcarra maintains his innocence.

Peruvians are frustrated. They have been told that by voting they can secure an honest government. But elected officials repeatedly turn out to be self-interested and corrupt. The public perennially mistakes its dashed hopes as a problem of the wrong people in the job. Yet as fast as they throw the bums out and bring in new ones, more scandals arise.

At the core of this dysfunction is a state with vast powers to redistribute wealth. The incentives to maintain the status quo are significant. Even voters who say they want less corruption may find that change conflicts with their self-interest. The siren song of populism draws them to politicians who can hand out plenty of government jobs and other goodies in a world of weak institutional checks.

That such power is abused is as predictable as human nature itself. So too is Peru’s grim future if the statist rabble-rousers demanding a new constitution prevail.

Write to O’Grady@wsj.com.