A new and severe respiratory infection has cancer-stricken President Hugo Chavez in a “very delicate” state, and his breathing has deteriorated, Venezuela’s government announced late Monday.

Communications Minister Ernesto Villegas read a brief statement on national television saying Mr. Chavez’s “worsening respiratory function” was tied to a weakening of his immune system.

Serious but not sombre, Mr. Villegas said the charismatic socialist leader had “a new and severe infection.” The state news agency identified it as a respiratory infection.

Mr. Villegas said Mr. Chavez, 58, had been undergoing “chemotherapy of strong impact, among other treatments.”

Mr. Villegas also took the opportunity to lash out at “the corrupt Venezuelan right” for what he called a psychological war seeking “scenarios of violence as a pretext for foreign intervention.”

Upon Mr. Chavez’s death, the opposition would contest the government’s candidate in a snap election that it argues should have been called after Mr. Chavez was unable to be sworn in on January 10 as the constitution stipulates.

Indeed, the campaigning has already begun, although undeclared, with Vice-President Nicolas Maduro, who Mr. Chavez has said should succeed him, frequently commandeering all broadcast channels Chavez-style to tout the “revolution” and vilify the opposition.

Mr. Chavez has run Venezuela for more than 14 years as a virtual one-man show, gradually placing all state institutions under his personal control. But the former army paratroop officer who rose to fame with a failed 1992 coup, never groomed a successor with his force of personality.