MANAGUA, Nicaragua (AP) -- Daniel Ortega, the Sandinista leader who battled U.S. efforts to overthrow him in the 1980s, has his best chance in 16 years to win back Nicaragua's presidency when a divided electorate votes on Sunday.

Ortega, who led Nicaragua from 1985-1990, has already made three unsuccessful attempts at re-election.

His success so far does not reflect a sudden surge in his popularity, as his current poll numbers are well below what he won in the last presidential election. It is due largely to a change in electoral law engineered by his party as well as his own ability to stand his ground while parties around him have splintered.

To win, Ortega needs just 35 percent of the vote and a five-point advantage over his closest opponent, the Harvard-educated banker Eduardo Montealegre. The last polls showed him with an easy lead over Montealegre, but just shy of the 35 percent he needs to avoid a runoff in December.

Ortega won more than 40 percent of the vote in the 2001 election, but was easily beaten by a united anti-Sandinista bloc. He would likely face the same obstacle this year if the election goes to a second round and eliminates three of the five candidates: Sandinista dissident Edmundo Jarquin, ruling party lawyer Jose Rizo and former Contra rebel Eden Pastora.

Initial results will be released around midnight Sunday EST with official final results expected by Wednesday.

Ortega probably would not even have a chance at winning the first round this election if the Sandinistas had not negotiated a change in electoral laws six years ago to eliminate the requirement that a candidate receive 45 percent of the vote to avoid a runoff.

But Ortega credits an improved image for his recent success. He has tried to moderate his radical leftist image by trading in his party's red and black for rose-colored banners preaching peace, love and reconciliation.

Subsidized oil from Venezuela has not hurt either, his opponents claim. Montealegre says an agreement between Chavez and the Sandinista-dominated Association of Municipalities was tantamount to buying votes for Ortega.

Ortega, who fought a war with the U.S.-backed Contras in the 1980s, accuses the United States of meddling in the election.

Montealegre argues that Nicaragua, the second-poorest nation in the Western Hemisphere, needs U.S. support to survive economically.

Ortega says he would maintain relations with Washington and promote trade with the U.S. and other nations, including Chavez's Venezuela. Roberto Rivas, the president of the Supreme Electoral Council, said Friday officials were investigating alleged phone calls to voters warning them that if Ortega won, "there will be war."

Fidel Lopez, a 40-year-old dive-shop owner in the beachside resort of San Juan del Sur, is convinced Ortega would take Nicaragua back to its wartorn past.

"Six months after his election, there will be people armed and ready to take him down," he predicted.

Some Ortega opponents say he would not be the front-runner today if Sandinista breakaway candidate and former Managua Mayor Herty Lewites had not died of a heart attack in July in the middle of his campaign.

Lewites was expelled from the Sandinista party last year even though polls showed he was more popular than Ortega at the time. His replacement, Jarquin, has not generated the same excitement.

Lewites campaigned against what U.S. officials call "the corrupt pact," a left-right power-sharing agreement between Ortega and former President Arnoldo Aleman, who has since been convicted of corruption and is under house arrest.

The pact gave the two parties shared control of the courts and anti-corruption agencies, as well as council overseeing Sunday's election. It also included the reduced vote requirement for a first-round victory.

Ortega says he is a new man who wants to unite the country, create jobs and build hospitals and schools.

He was 39 years old when he first became president in 1985 after heading the Sandinista junta that toppled dictator Anastasio Somoza.

After several years of economic chaos and a U.S.-backed guerrilla war against him, Ortega lost the 1990 election — ending Sandinista rule. He then launched two unsuccessful presidential campaigns.

Among the changes this time around, he chose a running mate who was once one of his worst enemies: Jaime Morales, the spokesman for the Contras.

As Sandinista leader, Ortega expropriated Morales' six-bedroom estate and still uses it as his campaign headquarters. They reconciled after Ortega offered to pay Morales for his former home. Morales said he decided to join Ortega's campaign because he preferred "the strange to the unknown."