The survey from pollster Analogias put support for Massa, the outgoing government's economy chief, at about 42% versus 34% for Milei, a combative self-described anarco-capitalist.
Political polling has been wildly off in Argentina in recent years, including ahead of last Sunday's first-round vote, when Milei led in nearly all polls but ultimately came in second to Massa by about six points.
The new poll also shows nearly 18% undecided in the head-to-head match-up, while about another 6% said they will vote for no one.
It also estimates Massa is winning about a third of those who supported last Sunday's fourth-place finisher, as well as almost 15% of those who opted for Bullrich.
Reporting by Nicolas Misculin; Editing by David Alire Garcia; Editing by David GregorioOur Standards: The Thomson Reuters Trust Principles.
Persons:
Sergio Massa, Patricia Bullrich, Javier Milei, Analogias, Milei, Wednesday's, Massa, Proyeccion Consultoras, Nicolas Misculin, David Alire Garcia, David Gregorio Our
Organizations:
por la Patria, el Cambio, Massa, Bullrich, Consultora, Thomson
Locations:
BUENOS AIRES, Argentina, South America's