Shaded by brand new elevated rail tracks, thousands of residents in the Thai city of Khon Kaen sit fidgeting as they wait for Prime Minister Prayut Chan-o-cha to arrive. Music booms through the speakers.

"The world has not lost hope, if it hangs on to goodness," a baritone croons as a montage of scenes flashes on giant screens, showing Mr Prayut handing aid to flood victims and wiping sweat from his brow. "Good people never die."

This is followed by a music video in a beguiling folk style, typical of this north-eastern region better known as Esan. "Vote for good people… stop voting for corrupt people," it urges.

There are no political party logos and banners here, but this is as close as it gets to an election rally for Mr Prayut, who appears most likely to remain as prime minister after Thailand's March 24 polls.

Treading gingerly through the labyrinth of new election rules, the former coup leader has turned down a request to speak at rallies organised by the newly formed pro-junta Palang Pracharath Party, which nominated him as its prime minister candidate.

However, his picture graces the party's posters. He has also toured crucial constituencies, inspecting train projects and extolling the achievements of his five-year-old military government.

While a handful of other political parties, such as the Action Coalition for Thailand and People's Reform Party, want Mr Prayut, 64, to return, it is the design of Thailand's new Constitution that will most likely ensure that outcome.

For a period of five years after the election, an appointed 250-member Senate has the right to choose a prime minister with the 500-member elected House of Representatives.

Since most of the senators will be picked by the ruling junta, this translates into a pro-military voting bloc occupying one-third of Parliament seats. Theoretically, pro-Prayut parties need only win 126 out of 500 seats in the Lower House to usher the former army chief back into power.

In the meantime, Lung Tu, or "Uncle Tu", as he is known, has been trying to portray a softer side.

For years after overthrowing the Pheu Thai Party-led government in a coup, he hurled gruff replies at reporters, frequently scolding critics for not appreciating his work.

His supporters shrugged it off as the authentic behaviour of a military man, contrasting it favourably to the polished manners of wily politicians.

These days, the junta chief tweets pictures of himself hugging children or posts a picture of his lunch of rice and soup on Facebook, saying "Delicious food doesn't need to be expensive". He has traded occasional scowls for crinkly smiles, and poses for pictures with his thumb, pinky and index finger raised to say "I Love You" in sign language.

"He was presenting himself as a strong military man for the past five years and now he is... trying to be nice, funny, lovable," says historian Charnvit Kasetsiri.

"I don't think he can turn it over just like that."

Coup-prone Thailand is familiar with retired generals wading into electoral politics, but analysts say the country is entering new territory.

This election is "a referendum on democracy", says Dr Titipol Phakdeewanich, the dean of Ubon Ratchathani University's political science faculty. "It's to show if this country wants to move on with democracy, or wants to return a dictator as leader."

Mr Prayut has said he overthrew the government in 2014 to prevent Thailand from sliding further into turmoil. However, critics saw it as the latest attempt by the royalist military establishment to dislodge the country's most successful politicians over the past two decades.

Rather than resolve Thailand's deep political conflict, the military has only suppressed it, analysts say. Mr Prayut's foray into politics has cast him as a partisan player in the deep political divide. "I don't think there is something in the middle anymore, especially in this election," says Dr Charnvit.

Palang Pracharath is trying to portray Mr Prayut as Thailand's saviour. An internal handbook launched last month says: "There's hardly anyone with such courage and determination to lead the country stably and who firmly adheres to the (state ideology) of nation, religion and monarchy. There may be only one person and his name is General Prayut Chan-o-cha."

People in Esan, the heartland of Pheu Thai's support, may still take some convincing.

The latest results from Khon Kaen University's E-saan Poll unit on March 13 show 43.6 per cent of respondents in the region saying they would vote Pheu Thai. The youthful Future Forward Party polled 23.3 per cent, with Palang Pracharath third at 11.7 per cent.

At the opening of Khon Kaen's railway station, Mr Prayut raises a fist in the air and asks the elderly folk before him: "I ask for love and unity, can you give them to me?"

"Yes", they chant.

"Yes! Clap your hands!" he orders. Shortly after, he heads upstairs to board a train, sent off by traditional dancers.

Down by the emptying ticketing hall, Ms Sayan Sittithum, 54, lingers to admire the grand new station. But when asked which party her province will support, she looks away disdainfully.

"This is Esan," she mutters. "Which party do you think is the strongest here?"