NAYPYITAW, Myanmar — Aung San Suu Kyi was set to be sworn in to Myanmar’s military-backed parliament today, taking public office for the first time since launching her struggle against authoritarian rule nearly a quarter century ago.

The 66-year-old opposition leader’s entry into the legislature heralds the start of a historic new political era in Myanmar, cementing a risky detente between her party and the government of President Thein Sein. The government has spearheaded months of unexpected reforms since taking power last year, including the holding of April 1 by-elections.

Suu Kyi’s National League for Democracy party will occupy too few seats to have any real power in the ruling party-dominated assembly. But the new lawmakers are also likely to bring a level of public debate to the legislative body that has never been seen as they prepare for the next general election in 2015.

The last time Suu Kyi’s party was set to join parliament was 1990, after a landslide election victory that was swiftly annulled by the army. The military remained in power until last year.

Suu Kyi’s personal ascent marks an astonishing reversal of fortune for a woman who became one of the world’s most prominent prisoners of conscience, held under house arrest for much of the last two decades. When the 1991 Nobel Peace Prize winner was finally released in late 2010, few could have imagined she would make the leap from democracy advocate to elected official in less than 18 months.

This week, Suu Kyi backed down in a dispute over the oath of office which, had it dragged on, could have spiraled into another crisis.

Suu Kyi and her colleagues had refused to join parliament when the latest session began April 23 because they object to phrasing in the oath that obligates them to “safeguard the constitution.” They want the word “safeguard” changed to “respect.”

But on Monday, Suu Kyi abruptly changed course, saying: “Politics is an issue of give and take. We are not giving up, we are just yielding to the aspirations of the people.”