For years he walked alongside Nobel laureate Aung San Suu Kyi, a quiet confidant as she campaigned for democracy in Myanmar. On Tuesday, with her blessing, Htin Kyaw will become the country's president.

A soft-spoken man with a penchant for literature and writing, Htin Kyaw gave up a career in the foreign ministry decades ago to help Suu Kyi, his childhood friend, with her political party. When Myanmar was under military rule, he ended up in the junta's prison along with other pro-democracy activists.

But until last week, Htin Kyaw was hardly a household name, and most people in Myanmar — or outside — could have never imagined that he would become the president of the country's first democratically elected government in more than a half-century.

Suu Kyi led her National League for Democracy party to a landslide victory in the Nov. 8 general elections, but is prevented from becoming president by a constitutional clause designed by the former military rulers who have been gradually letting go of power since 2011.

So she chose a trusted friend and adviser. She has repeatedly said she expects the president to be her proxy.

Htin Kyaw, 70, is the son of a national poet and the son-in-law of a founding member of the country's pro-democracy movement. He has known Suu Kyi, 71, since grade school. Their fathers were family friends, and Htin Kyaw has been at Suu Kyi's side almost constantly since 1992.

But he kept such a low profile that journalists were left scrambling to find out anything about Htin Kyaw when his nomination was announced last week. After all, he was only the nameless face often appearing behind Suu Kyi in pictures taken during her infrequent public appearances before she was freed from long periods of house arrests.

"Htin Kyaw is a very quiet man who loves literature," said Zaw Min Kyaw, who has known Htin Kyaw for more than 20 years. Zaw Min published a book compiling a series of articles Htin Kyaw wrote about his father, titled "My Father's Life," in 2009.

"He talks steadily and softly. He is such a kind person; very honest, quiet, and passionate, and lives simply," he told The Associated Press.

Under Myanmar's complicated electoral system, the president is elected by lawmakers of both houses of parliament. They chose from three candidates, one representing the lower house, one the upper house and one representing the military bloc, which has 25 percent of seats reserved for them. The candidate with the highest number of votes becomes president and the other two become vice presidents.

As the personal nominee of Suu Kyi, Htin Kyaw is expected to win the highest number of votes in elections set to take place Tuesday.

Suu Kyi nominated him "obviously to show that he is the most trusted person for her," said Zaw Min, 48, a former NLD member. "If this kind of person leads the country ... it will also affect positively on the people of this country."

Htin Kyaw is one of the first generation of graduates from Rangoon University, now the University of Yangon. He earned a bachelor's degree in economics in 1967 and a master's degree in economics in 1968, while also working as a lecturer there. He moved to the computer science department in 1970, and later studied computer science at the University of London for two years before returning home to work as a programmer and analyst until 1975.

Five years later, Zyaw Min said, Htin Kyaw then joined the government's foreign economic relations department, where he worked as deputy director. He resigned in 1992 — apparently because of his family connections to the opposition party — and took greater interest in the work of NLD, which was in the throes of a democracy campaign against a military junta.

At the time, his father-in-law, U Lwin, was sick and Htin Kyaw used to drive him to the party office. In the process he started helping Suu Kyi with issues relating to foreign policy, and became the key adviser on the party's outreach to foreign governments and embassies, even as the junta continued to throttle the democracy movement.

A watershed in his life came in 2000 when NLD workers, including Zaw Min, wanted to go to Mandalay on a campaign trip. They went to the Yangon train station to meet with Suu Kyi, who had been driven there by Htin Kyaw. But officials refused to sell them tickets, and the situation became tense.

Instead of leaving Suu Kyi at the station, Htin Kyaw "waited and waited because he knew the situation was not good," said Zaw Min.

In the end everyone was detained, including Htin Kyaw. Suu Kyi was returned to house arrest, and the other 84 activists spent the next 4½ months in the notorious In Sein prison.

Up to that point, and even after his release, Htin Kyaw "didn't really do much active politics as far as I know," said Zaw Min. "It's not like he was taking a big position in the political party, but over the years he ended up helping Suu Kyi a lot in party affairs."

Htin Kyaw is now the central committee member of Daw Khin Kyi Foundation, a charity named for Suu Kyi's mother.

"He is a very trusted friend of Daw Suu Kyi," said Zaw Min. They both went to the same elementary school in Yangon. Htin Kyaw is remembered by his acquaintances as a smart student who loved sports. At university, he played water polo.

"After he retired (from his government job), he became very quiet. He started spending a lot of time reading and writing articles," said Zaw Min.