The incumbent's clear victory had two immediate outcomes: It gave the Fernandez camp a welcome boost, albeit tinged with relief, and left the opposition plenty of food for thought over its flawed assumptions and miscalculated confidence.

It also exposed the government to risks that things could go badly wrong before the Oct. 23 election if economic problems continue to weigh down the electorate.

Both sides need to work to build their positions and Fernandez specially has to watch her step as her gain can easily turn into loss in the months ahead, analysts said amid intense discussion of the Aug. 14 aftermath.

Argentina faces major challenges to fix its economy, keep labor unions content in the months ahead and achieve a fairer income distribution and poverty reduction.

Workers' protests have dented the president's approval ratings before, especially after major farm stoppages in 2008-09, and numerous follow-on clashes between labor union representatives and the government.

The primaries' outcome showed Fernandez could win back voters lost in previous polls and sustain her primaries lead before the decisive Oct. 23 vote if the opposition fails to put up a strong fight.

Fernandez received more than 50 percent of the vote and was nearly 38 percentage points ahead of the closest candidate, centrist Radical Civic Union party congressman Ricardo Alfonsin. Former President Eduardo Duhalde, representing a conservative faction of the Peronist party, came third.

The opposition still has the potential to close ranks in a final push for power, analysts said.

Disappointed critics are banking on the economy becoming an issue before the election or labor disputes boiling over and pulling Fernandez down.

When Fernandez succeeded her husband, Nestor Kirchner, in 2007, skeptics saw her victory as implicit support for her husband, who steered the country through recovery after the economic crisis in 2001, when Argentina defaulted on its sovereign debt.

In 2008 her popularity rating fell to less than 30 percent after the farmers' revolt. But a boom in commodity prices enabled Fernandez to fund economic reforms and welfare programs.

When Kirchner died in October 2010 Fernandez's image suffered initially because many Argentineans believed her to be dependent on her husband. Soon after, however, Fernandez clawed back approval ratings and even surpassed previous ratings.

Analysts said her strong win in the primaries would prompt many Argentineans to reflect on the result and its impact on the Oct. 23 presidential election and would make voters more exacting in their assessment of her gains.