The Election Commission (EC) is being urged to ensure fair and transparent elections in the wake of extremely low public confidence in the integrity of the process in the run-up to the March 24 contest.
In the latest findings by the National Institute of Development Administration, or Nida Poll, more than 78% of participants believe vote-buying will be rampant.
Only 19% of the respondents felt the elections will be fraud-free while the remaining 3% were not certain if politicians and parties will resort to vote-buying.
Democrat Party deputy spokesman Jurit Laksanavisit said it is the EC's responsibility to restore confidence by tackling all forms of foul play.
"The EC should keep a close watch on the use of special powers to win the polls. The people should also block them from rising to power," Mr Jurit said without elaborating further.
Mr Jurit also said the electorate must shun vote-buyers, noting that politicians who throw money into getting elected will only try to recoup their loss later at the expense of the country.
With online campaigning set to play a major role, Pheu Chart deputy spokesman Rayus Boontam expressed concern over ambiguous wording about the practice in the election law.
"This could be exploited, and one thing we've learned from years of political crises is that legal wrangles can cause massive damage and a loss of faith," he said.
Parties last week attacked the rules on online electioneering, calling them trivial and full of discrepancies.
Mr Rayus also criticised the EC for imposing strict regulations concerning the use of social media.
He said social media is an inexpensive and easy-to-access channel that parties, especially small ones with scarce financial resources, can use to communicate with voters.
"Social media can create a level playing field and the EC should have promoted its use instead of introducing restrictions and causing panic among candidates," he said.
On Sunday, the Pheu Thai Party's chief strategist, Sudarat Keyuraphan, said the party is concerned about the regulations and its legal office will hold a meeting with its candidates to make sure they understand them and keep themselves out of trouble with the election monitor.
According to the findings of Nida Poll, almost 24% of respondents do not believe the candidates will be able to deliver on their promises while more than 53% said they were uncertain about the validity of parties' promises.
A large majority, 72%, of the respondents said they were eager to cast their votes after five years without an election. Only 19% said they were not particularly enthusiastic about it, while 7% said they were not excited about the prospect at all.
The Dusit Poll, meanwhile, found that 34% of respondents were fed up with the broken promises made by parties during previous campaigns while almost 33% said they had been disgusted by mud-slinging during electioneering in the past.
According to the results of the survey, about 33% would urge politicians to strictly follow the election regulations while 28% made it clear that they want the election to be free of vote-buying.
EC secretary-general Jarungvith Phumma said candidates and parties are sending in details about their planned online campaigns to provincial election offices ahead of the candidacy registration from Feb 4-8.
Both Nida and Suan Dusit polls were conducted nationwide.
Nida Poll surveyed a total of 1,250 people from Jan 23-24, while the Suan Dusit Poll questioned 1,132 people from Jan 23-26.
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