Brazil's Bovespa stock index.BVSP will rally or sink at the end of the year depending on the outcome of the nation's presidential election in October, a Reuters poll showed on Thursday, while Mexican shares will track economic growth higher.

Brazilian stocks are up about 4 percent in the year to date, mostly led by bargain-hunting after concerns over weak domestic economic growth and diminished global liquidity drove the Bovespa to its lowest closing level in around five years in late March.

Another major driver pushing the Bovespa forward has been a prospective change in the nation's leadership, which many market participants have accused of adopting policies that are detrimental to the private sector and minority shareholders of state-owned enterprises.

Some of the biggest daily gains registered in recent months have come after electoral polls showed a decline in President Dilma Rousseff's approval rating, though she still holds a lead.

"A (Rousseff) loss will please investors because it raises the chances of a lighter government hand in the market," said Luiz Roberto Monteiro, a trader with Renascenca in Sao Paulo.

Unlike recent polls, analysts surveyed last week were unable to provide an estimate for the Bovespa's closing level in 2014 without taking into account two scenarios:

Should Rousseff win re-election, the Bovespa will likely end the year at 51,250 points, a 4 percent decline from Wednesday's close.

The Bovespa is set to rally to 62,000 points, however, should Rousseff lose, up 16 percent from Wednesday.

"In principle, it will have a positive impact on the market," said Ariovaldo Santos, a trader with H.Commcor in Sao Paulo, highlighting shares of state-run companies such as Petroleo Brasileiro SA (PETR4.SA), electric utility Centrais Eletricas Brasileiras SA (ELET6.SA) and lender Banco do Brasil SA (BBAS3.SA).

Santos cautioned, however, that long-term structural problems are likely to keep weighing on the market despite the outcome, such as high inflation and a weak economy.

Other key risks cited by analysts include a decline in global liquidity as the U.S. Federal Reserve continues to wind down its monetary stimulus program, and weaker economic growth in top trade partner China.

Mexico's IPC stock index .MXX, which is nearly flat on the year, is likely to close the year at 45,519 points, according to the median forecast in the poll, a 6 percent rise from Wednesday.

"The performance we're expecting depends on stronger economic growth in the U.S. and Mexico alike following the slowdown we saw recently in Mexico," said Arturo Espinosa, an equities analyst with Santander Mexico.

Demand for Mexican stocks have been hit by weaker than expected growth in Latin America's No. 2 economy. Mexico's government has slashed expectations for growth to around 2.7 percent this year, leaving many stocks looking pricey given the outlook for earnings.