The Commoners Party (CMP) has refused to remove the words "military dictatorship" and "shackles" from its election campaign announcements on YouTube, according to party leader Lertsak Kamkongsak.
The CMP claimed the provincial election office in Loei has asked the party to drop the two words.
Mr Lertsak said the party's campaign advertisements asked why the country was being governed by elites while the majority of people are not represented in parliament.
The CMP was founded by people in the "lower rung", said Mr Lertsak, who is a non-governmental organisation advocate working on natural resource and environment issues.
The announcements said the party would serve voters who disagreed with the country being ruled by a military dictatorship and wanted equality.
They also mentioned how the people had nothing to lose except facing shackles, meaning that political changes come with risk.
The CMP is politically active in parts of the North and Northeast, having fielded candidates in 17 districts of Loei, Chiang Rai, Chiang Mai, Lampang, Sakon Nakhon, Surin, Kalasin and Nong Bua Lam Phu.
CMP poll candidate Sunthorn Hongchai said party members have fought against environmental destruction caused by gold mining operations, which had often landed them in court.
"In the more than 10 years of our fight, no MPs in our constituencies ever met us to offer us help. That's the reason we want to run for office ourselves," he said.
"Our country is where it is now because we have too many rich or educated MPs. Is that it?" Mr Sunthorn said.
The party has tried to woo voters by using leftover materials such as wicker bamboo trays in lieu of campaign posters.
CMP poll candidate Sunthorn Hongchai said some candidates in Sakon Nakhon have sprayed their candidacy numbers and names on discarded sheets of plastic.