CaracasMachado failed 3 return attempts Monday night, her party says.
Her return could decide whether Venezuela holds its first free vote in years.
Courts loyal to Maduro barred Machado from last year’s vote, which her stand-in is believed to have won.
The government denies blocking her return, though it freed dozens of prisoners last week after US-backed talks.
Rodriguez told the UN Venezuela would transition to “full democracy,” with no election date set.
Sources: Al Jazeera Online