Mr. Calderón — who by law is limited to one six-year term — says he has saved Mexico from becoming a failed narco-state. The offensive was necessary, he argues, because complicit previous governments, limp American efforts to tackle drug consumption and cross-border gun running, and changes in organized criminal markets had allowed the power and brutality of the cartels to get out of control. He has a point — but his party’s failure to find democratic ways to bolster state power and legitimacy, after one-party hegemony ended, is a large part of the story of why the cartels have yet to be brought to heel.

The damp-rag presidency of Mr. Calderón’s predecessor, Vicente Fox, of PAN, who was president from 2000 to 2006, deserves much of the blame. Mr. Fox frittered away the enthusiasm that accompanied his historic election and did almost nothing to reform the structures of government left behind by the PRI. Aside from an energetic, if doomed, push for an immigration agreement with President George W. Bush’s administration, he trundled along in a haze of frivolity, punctuated by a streak of malevolence he displayed by trying to block a popular leftist, Andrés Manuel López Obrador, from even running for president. That failed, but Mr. López Obrador lost by a whisker to the PAN candidate, Mr. Calderón, who successfully branded him an unhinged messianic radical, in 2006.

The second term for PAN, won by Mr. Calderón, meant further stagnation for Mexican democracy.

The one-term limit for many offices still means that politicians who want to further their careers barter in back rooms with their eye on the next post, rather than debate their record before voters in an effort to gain re-election. Judicial reforms, approved in 2008, have been underfinanced and slow to take effect. Regulatory agencies are too weak to impose their will on the monopolies and oligopolies that control the economy. Mexicans still dance to a tune played by a class of unaccountables, from influence-peddling union leaders to governors who rule their states as fiefs to TV networks that play favorites.

Corruption is so embedded in Mexico’s life and self-image that the revelations of kickbacks paid by Walmart to expand in Mexico drew little more than world-weary shrugs. Mr. Fox’s promises to go after “big fish” and Mr. Calderón’s pledge of “clean hands” have been all but forgotten.

THERE have been some silver linings in the PAN years. The colossal economic mismanagement of the final decades of PRI rule has mutated into a dogged commitment to stability. Transparency laws and aggressive news media are applying scrutiny to the powers that be. After an open debate, Mexico City has made abortion on demand legal (in the first 12 weeks of pregnancy) and recognized same-sex marriage.