What to know about Venezuela's election as Maduro faces the toughest race of his decade in power

CARACAS, Venezuela (AP) — Venezuela's self-described socialist government is facing a serious electoral challenge in a presidential election for the first time in decades.

President Nicolás Maduro, now in his 11th year in office, is being challenged by former diplomat Edmundo González Urrutia at the head of a resurgent opposition, as well as a field of eight other candidates. The official campaign period for the July 28 election kicked off Thursday.

Maduro, who has presided over an economic collapse that has seen millions of people emigrate, and his United Socialist Party of Venezuela have fended off challenges by barring rivals from elections and painting them as out-of-touch elitists in league with foreign powers.

This time, he promised to let the Unitary Platform opposition coalition participate in the election in a deal that brought his government some relief from crippling economic sanctions imposed by the United States. That respite, however, was short-lived as the U.S. reimposed sanctions amid mounting government actions against the opposition, including blocking the candidacy of opposition powerhouse María Corina Machado.