The opposition has pledged to use the upcoming Chiang Mai by-election as a platform to expose what it says are the ruling Pheu Thai Party's failures in running the country.
Democrat Kingkan Na Chiang Mai draws No.3 for the by-election.
Democrat Party deputy leader Siriwan Pratsajaksatru said the campaign will use the "Bangkok Model", aiming to repeat the opposition party's success in the March 3 governor election in the capital.
The tactic seeks to increase voter awareness of what the Democrats claim are Pheu Thai's failures in national administration.
Ms Siriwan said the campaign worked fairly well in the Bangkok governor poll, handing Democrat candidate MR Sukhumbhand Paribatra a second term in office with more than 1.2 million votes.
Ms Siriwan said the Chiang Mai electioneering will also uncover allegations of irregularities connected to Yaowapa Wongsawat, Prime Minister Yingluck Shinawatra's elder sister.
Ms Yaowapa has rarely been grilled politically in public. "But this time she will get a taste of it," a political source said.
It is widely expected that Ms Yaowapa, a former Chiang Mai MP in Muang and Saraphi districts in 2001 and 2005, will win the April 21 election due to her substantial support base in Chiang Mai's Constituency 3.
The constituency encompasses San Kamphaeng, Mae On and Doi Saket districts.
The source predicted Ms Yaowapa will have a relatively easy win in San Kamphaeng, her hometown, and Mae On, but Democrat candidate Kingkan Na Chiang Mai, also a former MP of the province, is a favourite in Doi Saket.
However, the source said Ms Yaowapa will have to address accusations by the Democrats that she manipulated transfers of local administration authorities.
Thanet Charoenmuang, a political scientist at Chiang Mai University, said Pheu Thai hopes that, if elected, Ms Yaowapa will be an MP "at the forefront" of the party, overseeing colleagues and coordinating with factions within the party.
A rumour had spread earlier that Ms Yaowapa needed MP status to become fully re-engaged in politics to help her brother Thaksin deal with rifts in the Pheu Thai Party and bolster ties with the red shirts.
The Democrats may not envisage a victory in the by-election, but will seize the opportunity to point out flaws it sees in the government.
Yesterday, three by-election candidates from three different parties reported to officials on the first day of candidacy registration.
Both Ms Yaowapa and Ms Kingkan are called "Daeng", a nickname also shared by another candidate, Thawisak Phupha, who leads the little-known Thai Rubber Party.
Ms Kingkan admits it will be hard to beat Ms Yaowapa but she still believes her work for the province will win the support of voters.
Ms Yaowapa said she is confident of securing victory in the by-election, saying it is time for her to serve her hometown.
The winner of the by-election will replace former Pheu Thai MP Kasem Nimmonrat, who has given up his seat citing health problems.
Pheu Thai’s Yaowapa Wongsawat after drawing No.2 yesterday.
About the author
Writer: Nauvarat Suksamra & Cheewin Sattha