A popular ex-wrestler and a physician, the first woman to seek Mongolia's top office, are the main rivals to the Harvard-educated incumbent in Wednesday's presidential elections, but neither is likely to wrest the job from him.

The election campaigning in this northern Asian nation has been dominated by debate over corruption, which President Elbegdorj Tsakhia hopes will work in his favor -- throughout his 4-year term, the former journalist has attacked bribery and embezzlement, weeding out graft in the national airline, public welfare funds and among the custodians of Mongolia's vast mineral wealth.

But he has also been accused of shielding his party members from corruption investigations.

"I'm your son. I know your pain and struggles," Elbegdorj, 50, told cheering supporters at a final campaign rally Sunday in the capital, Ulan Bator. "I know exactly what I will do if I'm re-elected. I will continue my fight against corruption and finish what I already started."

This year's election has again raised the question of how best Mongolia, a staunch U.S. ally, should benefit from its boom in the mining of coal, copper, gold, and other minerals. The newfound wealth has propelled the economy to dizzying heights, but also contributed to soaring inflation and further skewed the uneven wealth distribution in the landlocked country, squeezed between China and Russia.

Polls show Elbegdorj, of the ruling Democratic Party, with a strong lead over his rivals.

Elbegdorj, who has a degree from Harvard University's Kennedy School of Government, has also been highlighting his political origins as a leader of the 1990 protests that ended 70 years of one-party Communist rule and gave birth to a thriving democracy in a region better known for stern dictatorships.

He was elected president in 2009 after serving two terms as prime minister. He lives with his wife, mother and 25 children of whom 20 are adopted.

Along with fighting graft, he has promised to enact further legal reforms, increase public participation in government decision-making, and boost the Alaska-sized nation's participation in global institutions.

"Before Elbegdorj, nobody dared touch these corrupt officials protected by their party leaders," said retired Ulan Bator accountant Tungalag Tsedevdorj, a supporter of the president.

"Now we are hearing and seeing about the arrest and jailing of corrupt government officials," Tungalag said.

Elbegdorj's main rival, opposition Mongolian People's Party lawmaker Baterdene Badmaanyambuu, is a former wrestling champion who has portrayed himself as a clean politician committed to upholding national unity and fighting the environmental degradation brought by the mining industry.

Mongolians have huge respect for their traditional burly wrestlers, who compete bare-chested in boots and leather shorts, and Baterdene has successfully leveraged that popularity to win three terms to the Great Hural, Mongolia's parliament.

Baterdene, who towers over most of his compatriots with a height of 177 cms (5 feet 10 inches), is one of Mongolia's most successful wrestlers ever. He is a 11-time winner of the Mongolian national competition of Naadam that combines horse racing, archery and wrestling.

Baterdene, who also holds a master's degree in law, has vowed to overcome regional rivalries in the herding nation of 3 million people, a third of whom are poor, further root out corruption, and rid law enforcement and the justice system of political influence.

A third candidate, Health Minister Udval Natsag, is Mongolia's first woman to vie for the presidency and a staunch backer of former President Enkhbayar Nambar, now serving time in jail for corruption.

Elbegdorj's Democratic Party also controls the legislature under Prime Minister Altankhuyag Norov, although elections for that body are not due until 2016.

Baterdene, who is No. 2 in the race, has pledged to review a multibillion-dollar investment agreement signed with Anglo-Australian mining giant Rio Tinto, and has sworn to fight corruption regardless of who is implicated.

"I will not discriminate based on the notion that this is my party member or my brother," he said.

Baterdene, 49, has himself faced unproven accusations that he acquired a former state farm on the cheap through a murky privatization deal, and — perhaps most seriously in a land where herd animals have long been the basis of survival — sold hay bales to China in the middle of calamitous winter blizzards.

Critics of the president say he and his party are using the anti-corruption campaign as cover for politically motivated attacks on Baterdene's Mongolian People's Party. They point out that no Democratic Party members have been investigated or arrested by the country's anti-corruption body, the Independent Agency Against Corruption, run by Elbegdorj's allies, and say the judicial and law enforcement branches have effectively become Democratic Party auxiliaries.

Third-running Udval has sought support from female voters and also raised complaints that deals with foreign mining firms have failed to benefit ordinary Mongolians and threaten the country's economic independence.

Udval, 59, began her career as a neonatology doctor in 1978 and held various senior medical positions before entering politics in 2011. She was appointed health minister last year.

"Mongolia is facing a new choice. It is time to decide whether Mongolia can exist or not. If we can't make a new choice, we face the prospect of living as the colony of a foreign people," she told supporters.