Two former officials are on the run, accused of secretly leading a criminal group. Their old boss, now a powerful senator in the president’s party, is being grilled over what he knew.

And the timing could not be worse for Mexico’s president, who faces the corruption scandal as President Trump doubles down on accusations that drug cartels have the Mexican government in their grip.

At the scandal’s center is the senator, Adán Augusto López Hernández, a former interior minister and governor of Tabasco State, and a close confidante of former President Andrés Manuel López Obrador. Two men Mr. López appointed in Tabasco, a secretary of security and state police chief, are now wanted by the Mexican government and Interpol, facing charges of leading a criminal group involved in drug trafficking.

Mr. López has not been accused of any crimes, and President Claudia Sheinbaum and her ruling party, Morena, have closed ranks behind him.

But the case strikes at the heart of one of Mr. Trump’s most sensitive accusations: that Mexico’s political elite is unwilling to purge itself of the corruption that has long provided the cartels cover and impunity. The Mexican government has denied those allegations.

The scandal comes after Mr. Trump pushed Ms. Sheinbaum to allow U.S. troops to deploy inside Mexico to combat the cartels. Although the United States and Mexico on Thursday extended trade talks, Mr. Trump has repeatedly threatened steep tariffs to pressure Mexico into doing more against cartels and drug trafficking.