Montevideo, Uruguay (CNN) -- Uruguayans electing a new president in Sunday's runoff election will choose between a former guerrilla fighter jailed for 14 years and a politician who already has held the office.
Jose Mujica, a former Marxist Tupamaro guerrilla who was the top vote-getter in the October 25 election, is being challenged by Luis Alberto Lacalle, who was president from 1990-1995. Neither candidate received more than 50 percent in the first round of voting, forcing Sunday's runoff.
Third-place candidate Pedro Bordaberry, who was eliminated, threw his support behind Lacalle. It was not clear how much weight his backing will carry. Mujica led last month with about 48 percent of the vote to 29 percent for Lacalle. Bordaberry won about 17 percent.
"In politics nothing is certain," said political scientist Daniel Chasquetti. "Something unforeseen could happen. It would take a very important event for a segment of [Mujica] voters to change their votes. Normally, these things don't happen. We just have to wait.
"Like in soccer, the games must be played and people will go to the polls Sunday."
Flooding in northern Uruguay has displaced around 2,000 residents and threatened to disrupt voting in the area, but government officials said Friday they were dispatching seven helicopters to take ballots to the inundated zones. Election officials also said they were making provisions for those who may have lost identification in the flooding.
By law, campaigning ended at midnight Thursday. Both candidates held boisterous rallies Thursday night, each vowing unity after the election.
"No one is against anyone here," Lacalle told supporters.
At his gathering, Mujica said, "What unites us is much more than what separates us."
Known to supporters as El Pepe, Mujica belongs to the same Broad Front Party as popular President Tabare Vazquez Rosas. Both men are considered leftists.
Lacalle is considered more conservative.
Analysts before last month's election said neither Mujica nor Lacalle is likely to take Uruguay down a different path.
"You'd scarcely notice a difference in terms of which one of them is elected," said Larry Birns, director of the Council on Hemispheric Affairs, a liberal Washington-based think tank.
"No one expects any dramatic change in Uruguay no matter who wins," said Peter Hakim, president of the Inter-American Dialogue, a Washington-based independent policy center. "Uruguayan politics is pretty stable."
With little difference between the two candidates on policy, voters may look for other factors.
"I believe that this election is very interesting because for the first time in the history of Uruguay in addition to political postures and programs, which always affect the outcome to a degree, the election will be affected greatly by the personal attractions and weaknesses of each candidate, which the public can clearly discern," said Uruguayan sociologist Cesar Aguiar.
Mujica, 74, was imprisoned for 14 years and released in 1985 when democracy was restored to Uruguay after a 17-year dictatorship. He was minister of livestock and agriculture from 2005-2008 and is now a senator.
"He is the man who talks and dresses austerely," said analyst Gabriel Pereyra. "He is the man who communicates and talks the language of the people."
Analyst Rosario Queirolo describes Mujica as "a person who somehow lives what he preaches and is an antipolitician in another way. He doesn't very well fit the image of a president we have in Uruguay."
Mujica has played down his connection with the violent Tupamaros, who were defeated in 1973. Not that it seems to matter now, Birns said.
"That's a long time ago and really plays no role in his profile," he said.
Lacalle, 68, was president from 1990-1995. A lawyer and former senator, he lives in Montevideo's best neighborhood, Carrasco. He said during a previous corruption investigation he is worth $2 million, which "isn't seen well in Uruguay," Pereyra said.
The ex-president is a traditional politician from a longtime political family, said analyst Alfonso Lessa.
"Lacalle in his government put forth policies that were clearly liberal with respect to privatization," Lessa said. "Today he's not putting forth those policies. He's had a change."
Still, Hakim said, Lacalle has not become extremely conservative.
"Lacalle has a reputation of being a person of center right," he said. "There's really no right wing in Uruguay."
The Council on Hemispheric Affairs' Birns described both men using nearly identical language.
"Mujica is an uninspiring figure who is considered to be durable but not particularly inspired," he said. "You're not going to get any flashes from him. He's a meat-and-potatoes type of guy."
Lacalle, Birns said, "is an uninspiring figure. He doesn't have a particular personal following."
Bruce Bagley, dean of the Graduate School of International Studies at the University of Miami, also didn't see much difference.
"They both fit into the mold of Uruguayan leaders in recent years," he said last month.
The next president will have to address governmental reform, education and public safety, Pereyra said.
"International comparisons with hard facts show that Uruguay is a much more secure country than the vast majority of Latin American nations," sociologist Aguiar said. "But even so the public perception is that it is increasingly becoming more insecure."
Uruguay is one of the smallest Latin American countries, about the size of Washington state. But it is also considered one of the most economically developed. The nation has a strong political system and social welfare programs, Hakim said.
Uruguay, on South America's southeastern coast, has a population of 3.5 million, 92 percent of whom live in urban areas, according to the CIA World Factbook. The vast majority of them are of European descent.
"It's a country that keeps chugging along," Hakim said. "The political fights are very serious, but the governments stay the same. Whoever wins, Uruguay will continue to be Uruguay."
CNN's Arthur Brice in Atlanta, Georgia, and journalist Dario Klein in Uruguay contributed to this report.