ELIZABETH JACKSON: Thaksin Shinawatra's dramatic return to Thailand this week was welcomed by his adoring fans and the former prime minister's political colleagues.

He was emotional as he set foot on Thai soil for the first time in almost 18 months, after he was ousted from office in a military coup in 2006.

But his presence is making more than a few people nervous, among them Thailand's new Prime Minister.

While Mr Thaksin says he's not at all interested in politics anymore, very few people believe him.

And as Thais vote in new Senators today, in the final stage of the transition back to civilian government, there's every reason to wonder where Thai politics might be in another 18 months.

Our South East Asia correspondent Karen Percy reports.

NITIPONG HONARK: This is nice, I love this song. It's beautiful.

KAREN PERCY: Nitipong Honark is one of the best known men in Thailand's music industry.

(Song in background)

KAREN PERCY: We are listening to a song he wrote for superstar Bird from the artist's latest album.

A popstar himself, turned songwriter, turned music promoter, Mr Nitipong is now hoping to become a member of Thailand's Senate.

NITIPONG HONARK: Just because I'm older, I'm older, and everybody older they have tough ideas. More idea, more view, the point of view is wider.

KAREN PERCY: Mr Nitipong is one of more than 30 candidates vying for a seat in Bangkok province.

(to Nitipong Honark)

Will you get inspiration, different inspiration from sitting in the Senate maybe? Will you write songs based on the Senate and events that you might come across there?

NITIPONG HONARK: You think I can do it?

KAREN PERCY: I don't know.

NITIPONG HONARK: Write a song about politics? No, no, no, no. A song about Parliament? Yukky. It shouldn't be a song

KAREN PERCY: Nitipong Honark is well aware of what some people might think.

NITIPONG HONARK: You know you are a composer, how can you run the country? How can you have the idea for the country?

I said what? So OK in the Parliament, you should have only the guys who learn law? Only that? So OK now if true like that, I told everybody no.

KAREN PERCY: But he also thinks he has something to offer.

NITIPONG HONARK: So when I look at the television, I look at somebody that runs my country, hey he said something stupid. He's more stupid than me. I think I am stupid and I'm so, you know you know when I'm so. But he? Why that guy talk something so stupid?

(sound of Rosana Tositrakul speaking)

KAREN PERCY: Rosana Tositrakul is also seeking to represent Bangkok.

She's been a tireless anti-corruption campaigner for the past decade.

In one famous case she took on Thailand's biggest oil company and won.

She also heads a foundation that specialises in holistic medicine.

ROSANA TOSITRAKUL: This is you take for cough, and this one is a cinnamon mixture good for your stomach.

KAREN PERCY: On the day we visit her at one of the foundation's clinics, she's drawing some parallels between her current job and the one she's aiming for.

ROSANA TOSITRAKUL: The wellbeing is not only our physical, our mind, but it means the society, environmental, and spiritual health. That is the meaning of holistic health, so I think that I do not get out the theme of the health, the holistic health.

So the anti-corruption activity is a part of the social health, so I think that all this experience and background, I think I this will help a lot to be working in this new activity as a Senator.

KAREN PERCY: Miss Rosana won a senate seat in Bangkok in April of 2006 but she never sat in the chamber because of the political turmoil of that year.

The election results were annulled after complaints about then prime minister, Thaksin Shinawatra, and his Thai Rak Thai Party.

Then came the coup.

ROSANA TOSITRAKUL: Since the period of prime minister Thaksin, the checks and balance is lacking in politics and that caused the problem of the conflict of interests and he was accused of a huge corruption. And we hope that such a crisis should not continue, if we can really settle up the check and balance in the politics system.

KAREN PERCY: When he returned this week the first thing Thaksin Shinawatra did was report to court to address the corruption claims against him.

One case centres on a land deal involving his wife.

As well the Attorney-General accuses him of hiding assets and avoiding tax.

And investigations are still underway into the controversial multi-billion-dollar sale of his family's telecommunications company two years ago, the event which ultimately led to the coup.

(sound of Thaksin Shinawatra speaking)

KAREN PERCY: During a press conference this week he told reporters that he was sorry for the pain he had caused the country.

At the time he was deposed, tensions between his supporters and his opponents had spilled onto the streets.

And that's why Thailand's military leaders say they stepped in.

Now the billionaire businessman is talking of unity and harmony and wanting to live a peaceful and quiet life.

(sound of Thaksin Shinawatra speaking)

Thaksin Shinawatra was the country's most successful politician, the only leader to win consecutive elections.

He says now that he no longer wants to be involved in politics.

But he has changed politics in Thailand forever.

And even the political novice like Nitipong Honark can see what's been going on.

NITIPONG HONARK: You know, Thai people, most of them they are poor and they are happy with short term happiness.

KAREN PERCY: Mr Thaksin and now the new government have courted the poor who make up the bulk of Thai voters.

NITIPONG HONARK: When the lower class love this guy, the middle class and upper will hate him.

KAREN PERCY: In Thailand, senators are not allowed to be aligned with political parties in order to ensure their independence.

The military junta which ruled until December made changes to the senate to try to reinforce that.

There are now fewer senators, 150 in all and 74 of them have already been appointed.

In this vote there are 76 senate seats up for grabs, one for each of the Kingdom's provinces.

Under the old system, there were 18 seats in Bangkok, now there's only one.

That's going to mean one of our interviewees will miss out.

ROSANA TOSITRAKUL: It's not fair anyway, but we cannot do anything about that, many people said it's not fair. But anyway?laughs),.

NITIPONG HONARK: I'm afraid that I'm going to win. (laughs) You know it's going to change my laugh so much.

KAREN PERCY: This is Karen Percy for Correspondents Report.

ELIZABETH JACKSON: You don't hear that said too often.