The news that Mexican President Enrique Pena Nieto apparently plagiarized nearly 29 percent of his law school thesis couldn’t have come at a worse moment for Mexico. It will further weaken a president whose reputation is already tarnished by corruption scandals, at a time when his most important endeavor — Mexico’s education reform — is seriously threatened.

I don’t agree with some Mexican commentators who have minimized Pena Nieto’s plagiarism by painting it as a juvenile peccadillo, or tried to excuse it because it is a widespread practice among Mexican students, or who have criticized Mexican journalist Carmen Aristegui, who runs the website Aristegui Noticias, for blowing the case out of proportion.

Aristegui and her investigative team did what journalists are supposed to do: expose what politicians want to hide from the public. If the report is true — and so far nobody has proven otherwise — the journalists deserve praise for their work.

According to the report, Pena Nieto plagiarized 197 of the 682 paragraphs of his 1991 law degree thesis on Mexico’s presidential system. It happened in 1991, when the current president was 25 years old and obtained his law degree at the Universidad Panamericana.

Some Mexican newspapers are noting that top officials in other countries — including former Hungarian president Pal Schmitt, former Romanian prime minister Victor Ponta and three recent German cabinet ministers — were forced to quit their jobs for allegedly plagiarizing their theses.

(The exception to the rule is Russian President Vladimir Putin, who, according to Brookings Institute researchers, plagiarized much of his 1997 doctoral thesis in economics, without any known political consequences.)

All of this comes on the heels of several other scandals that have affected the Pena Nieto government, including a dubious bid — since nullified — for construction of a $3.7 billion Mexico City-to-Queretaro bullet train, the purchase of a $7 million house from a government contractor by Mexico’s first lady, and, most recently, controversial real estate payments by a businessman for the first lady’s apartment in Miami.

Unfortunately for Mexico, the latest blow to Pena Nieto’s reputation will make it more difficult for him to save what’s left of his most important accomplishment: an education reform to start evaluating Mexico’s 1.2 million elementary school teachers.

The reform was aimed at putting an end to the country’s age-old practice in which teachers literally sold their jobs — sometimes for about $10,000 — or passed them on to their children, or got the job because they were union loyalists, regardless of their academic records or teaching skills. Under the reform, 150,000 Mexican teachers have already been evaluated, in a gradual process that should last about six years.

Studies have shown that one of the main reasons behind Mexico’s mediocre economic growth in recent decades has been its lousy education system. And a key reason for that has been the country’s powerful teachers’ union leaders, most recently the CNTE union, blocking education reforms.

This week, the CNTE declared a national teachers’ strike, which shut down nearly half of the schools in Oaxaca and Chiapas, two of Mexico’s poorest states.

Mexicanos Primero, an influential nongovernment advocacy group that fights for quality education, has called on Pena Nieto to cancel its financial subsidies to the CNTE. It says — rightly — that the CNTE is sabotaging Mexican children’s constitutional right to receive a good education.

But Pena Nieto, hurt by previous scandals, had already made significant concessions to CNTE leaders. And the latest plagiarism affair is likely to make him even more afraid of confronting the union out of fear that their street protests could effectively shut down parts of the country, pro-education advocates say.

My opinion: If the report about Pena Nieto’s plagiarism is accurate, the Universidad Panamericana should invalidate Pena Nieto’s law degree. But Mexicans should detach Pena Nieto’s blunders from Mexico’s urgent need to evaluate its teachers. Pena Nieto’s presidency will be history in two years, but millions of Mexican children risk getting a bad education that would condemn them to poverty for many decades.

— Andres Oppenheimer is a Latin America correspondent for the Miami Herald.