Even before her latest health scare, Argentine president Cristina Fernández de Kirchner was appearing increasingly like a lame-duck president.

Prevented from running for reelection under the two-term limit in the Argentine constitution, Kirchner’s ruling Frente para la Victoria (FpV, the Front for Victory) was already struggling in midterm elections that will determine nearly half of the Argentine legislature.

But Fernández de Kirchner was rushed to the hospital for emergency surgery to remove blood from the surface of her brain, which followed a previously undisclosed subdural hematoma suffered after the president fell in August.  She was instructed by doctors to rest for 30 days, all but guaranteeing that the leading figure in Argentine politics would be on the sidelines as the country votes.

That might actually be good for the FpV’s chances, given the unpopularity of kirchnerismo these days — a decade after her husband Néstor Kirchner first won election, Fernández de Kirchner leads a government that’s struggling to stop inflation, slow rising crime and turn around a weakening economy.  The Argentine government’s dysfunctional exchange rate policy has led to the emergence of a black market for US currency.  Moreover, Fernández de Kirchner is still battling some of the holdout creditors from Argentina’s 1999-2001 debt crisis even as Argentina remains shut out from capital global markets, which has left the Argentine treasury sometimes grasping for liquidity.

Meanwhile, her former ally Sergio Massa is leading the charge against her in the province of Buenos Aires, by far the largest province in Argentina (it’s home to 15.5 million of Argentina’s 41 million residents). Massa, also a center-left peronista, served as the chief of the cabinet of ministers from 2008 to 2009 before winning election as the mayor of Tigre.  But he’s broken with Fernández de Kirchner in the midterm elections, and he’s founded a rival entity, Frente Renovador (Renewal Front).  As Tigre mayor, he’s focused on crime prevention, and as he looks to the national stage, he’s also emphasized reducing crime and corruption.  As a peronista alternative to kirchnerismo, Massa has defined himself as a business-friendly, center-left candidate, who’s embraced the push for greater social and economic justice over the past decade, but who prefers a less unorthodox approach to economic policy.

Massa’s Renewal Front defeated the Front for Victory in August’s open primaries — a sort of dress rehearsal for the actual midterm elections — by a margin of 35.1% to 29.7%, a gap that could grow on Sunday as Massa’s popularity has grown.

Argentines will choose determine one-half of the composition of the 257-member Cámara de Diputados (Chamber of Deputies) of the lower house of the Argentine National Congress and one-third of the composition of the 72-member Senado (Senate), the upper house.  Due to the staggered nature of elections, and the fact that the Argentine opposition did much better in the 2009 midterm elections than in the 2011 general election (when Fernández de Kirchner easily won reelection), the FpV will only be defending 38 of its 116 seats in the Chamber of Deputies.  So there’s still a wide chance that the kirchneristas will still control the legislative branch of government — in any event, the FpV will almost certainly remain the largest party in the Congress, and because of the regional nature of Argentina’s many opposition parties, the FpV will still probably win the largest number of votes in the October 27 midterms, notwithstanding its unpopularity.

But the once-high hopes that the FpV would consolidate its 2011 gains and win a two-thirds majority — enough to amend the Argentine constitution to allow Fernández de Kirchner to run for a third consecutive term — were long ago shattered.

The only other national political movement is the center-right Unión Cívica Radical (UCR, Radical Civil Union), which also expects to make gains — it placed first in five of Argentina’s 23 provinces in the August primaries, including the large western Mendoza province.

In Córdoba, the country’s second-most populous province, the peronista alternative Unión por Córdoba (Union for Córdoba) won 30.1% in the August primaries, pushing the kirchnerista FpV into fourth place.  In Santa Fe, the third-most populous province, a wide coalition among socialists, progressives and the UCR won 41.1% of the vote, pushing the FpV into third place.

There’s been little since the August primaries to suggest that Fernández de Kirchner has gained any ground, which leaves two threshold questions for Sunday:

• Will the kirchneristas retain a majority in Argentina’s Congress?
• Will Massa’s likely win in Buenos Aires province be so thorough that he becomes the frontrunner in the October 2015 presidential election?

Though its $711 billion economy (on a PPP basis) pales in comparison to Brazil’s $2.3 trillion economy or México’s $1.7 trillion economy, Argentina still features the third-largest economy in all of Latin America — and that means that the 2015 presidential election will be crucial to the region’s economy, especially with the chance that the pragmatic Massa will win.