Argentina's presidential election is headed for a November 22 runoff between incumbent Cristina Kirchner's chosen successor Daniel Scioli and conservative rival Mauricio Macri, partial results indicated Monday.

Business favorite Macri led the count with 36 percent of the vote to 35 percent for Scioli, with just more than two-thirds of polling stations reporting -- though most results from Scioli's stronghold, Buenos Aires province, had yet to arrive.

Under Argentine electoral law, in order to win outright, a candidate must claim more than 45 percent of the vote, or at least 40 percent with a margin of 10 points over the runner-up. The runoff will be the first in the country's history.