"The real story here is that even in a situation where the playing field is so far from being level, Capriles has a chance of winning the presidency. The significance of that shouldn't be underestimated," Arnson said.
Arnson pointed out that in the months leading up to the election, Chávez had greater access to media than Capriles, and also the opportunity to use state funds at the service of his campaign.
But she said that Capriles remained a strong challenger in this election, because Venezuelan opposition parties kept a united front. In addition, high crime rates, inflation, power shortages and other problems that have come to characterize the Chavez administration provided fertile ground for Capriles to gain new supporters.
"All of those things would naturally give a challenger a major advantage," Arnson said. "What's limited that advantage is that the basic playing field is skewed very heavily in favor of the incumbent."
"If Chávez wins and it's a narrow victory, it's going to be very hard for a lot of people to accept that it was free and fair," Arnson added. But she noted that Chávez's health is in frail condition after undergoing several cancer surgeries, and there is a real possibility that he could die in office if he wins on Sunday.
Elections for state governors and for Venezuela's National Assembly are also coming up soon, Arnson said. "The opposition has an incentive to hang in there and try again in a couple years."