CARACAS—The presidential election in Venezuela this Sunday really shouldn’t be this close. Counting on his legendary charisma and a dizzying oil boom that has brought nearly $1 trillion into state coffers during his tenure, Hugo Chávez probably thought he could coast to a third six-year term.

But then, reality went off-script. The comfortable poll lead he’d held for most of the year vanished in the last ten days. As the campaign draws to an end, Sunday’s vote is best seen as a toss-up. What happened?

At first blush, it’s mystifying. In an increasingly autocratic petrostate, the advantages of incumbency are so deep, it really ought to be a walk.

Take access to the media. Three minutes per day per broadcast outlet. That’s how much advertising each candidate is allowed in Venezuela in the weeks leading up to a presidential election. That’s six thirty-second spots, no more. To long suffering TV watchers in U.S. battleground states, that must sound like paradise. There’s a catch, though. While each candidate’s campaign is allowed no more than 3-minutes, the government can run as many “institutional” ads as it wants to promote its work. And in Chávez-era Venezuela, such ads are generally indistinguishable from the official campaign ads, down to using designed-to-look-alike logos.