The resounding victory by Move Forward Party (MFP) candidate Pongsathorn Sornpetnarin in the Rayong by-election over the weekend symbolises voters' thirst for new politics.
Mr Pongsathorn bagged nearly 40,000 votes -- or 60% of the turnout -- in Constituency 3 which covers Klaeng district, compared to more than 26,300 votes collected by Banyat Jetnajan, a well-known figure who stood for the Democrats.
The 56% turnout for a constituency with more than 122,000 voters is considered satisfactory for a by-election.
This is the second big victory for the MFP in the eastern province that ranks as the former stronghold of the Democrat Party and the Pitutecha family. The MFP beat its rival in the May 14 election, sweeping all three constituencies and shocking the incumbent.
The Sept 10 by-election aimed to fill a seat left vacant by the MFP's Nakhonchai Khunnarong, who was disqualified and resigned due to a past conviction and prison term for a theft committed 24 years ago when he was 20.
This is the first time Mr Pongsathorn has competed in a poll: he previously served as campaign assistant to Mr Nakhonchai, who is facing criminal and civil action on the grounds that he ran in the May 14 election despite being aware he was ineligible.
Some pundits expected Mr Pongsathorn would struggle given the damage to the party's image after his predecessor's resignation.
Yet the Rayong voters proved them wrong. Evidently, the MFP is even more popular than the candidate was, as Mr Pongsathorn raked in 11,000 more votes than Mr Nakhonchai.
In fact, several analysts interpreted the poll results as representing public disapproval of what's going on in national politics, particularly Pheu Thai's embrace of the military-leaning Palang Pracharath Party (PPRP) and United Thai Nation (UTN) Party, to its coalition, dumping the MFP despite all its pre-poll promises.
In short, this is the way voters show their prowess, giving politicians lessons, democratically.
More importantly, while the Democrat Party is not a coalition partner of the Srettha Thavisin government, it still represents the conservatives.
Several Democrats voted against the party's resolution to support Mr Srettha during the premiership selection on Aug 22, yet he still won the top job and subsequently formed a coalition.
The Sept 10 by-election is an ideological battlefield between those who identify themselves with new politics and the conservatives. It's not a coincidence that the Democrat Party was the only party fielding a candidate against the MFP.
The Democrats' acting party leader, Sathit Pitutecha, said the party obtained the consent of other members of the previous coalition government to run alone in the Sept 10 by-election to avoid splitting votes.
In a media interview on Monday, Mr Sathit admitted defeat.
He said there is a difficult road ahead, not only for the country's oldest political parties but also for those in the conservative camp.
The MFP's vivid victory is a sharp contrast to the lacklustre policy statement by Prime Minister Srettha, who began his term on Monday.
PM Srettha and his coalition partners should be prepared for tight scrutiny, not only from the MFP, but also by the public. The Sept 10 by-election, which is a challenge to the status quo, is just the start.