Pahor, whose own, center-left government fell last year because it was unable to tackle the economic crisis, has been sympathetic to Jansa's position, telling the AP that "I know what it means to be the prime minister at the time of crisis."
Although he is Jansa's political opponent, Pahor has supported some of the austerity moves, saying that reform is the only way out of the crisis and that Slovenia must show to Europe that it was able to pull out of trouble on its own.
Analyst Tanja Staric believes that Pahor won support by "systematically building an image of a politician who shares the destiny of the people."
Turk — a fierce critic of the reforms — has argued that Jansa's cost-cutting has not been equally distributed and will only hurt the poor.
Turnout among Slovenia's 1.7 million voters was lower than in the first round — in another sign of voters' discontent.
Worried Slovenes said they hoped the election would bring a sense of security.
"I think things will start to calm down from today," said 86-year-old retiree Mihael Grund, who ventured out early despite drizzle and cold to cast his ballot. "We have had so much tension recently and that is a big worry for us."
Thousands joined demonstrations in the capital of Ljubljana on Friday and in the second-largest city of Maribor earlier in the week. Both rallies ended in riots, with police using water cannons and tear gas to repel rock-throwing extremists.
Some Slovenes, like 35-year-old high-school teacher Igor Vulic, say no politician can bring about any change and that Slovenia needs new leaders.
"They should just all go," he said.
Ali Zerdin contributed to this report.