UDD chairwoman Tida Tawornseth and her husband, Weng Tojirakarn, marched alongside red-shirt supporters in Ayutthaya province with banners backing the Feb 2 polls.
Around 100 attendees took to the streets to voice support for the caretaker government and denounce People's Democratic Reform Committee (PDRC) leader Suthep Thaugsuban for inciting violence in the country.
A larger rally was meanwhile held in Khon Kaen province with around 5,000 UDD members, led by Adisorn Piengket, Nattawut Saikuar and other Pheu Thai Party MP candidates.
The demonstrators marched in the northeastern city to promote the election and challenge anti-government protesters to fight Pheu Thai in the polls, rather than through street protests.
Tanik Maseepitak, a red-shirt coordinator for the region, said the red-shirts would set up their own rally stages to counter allegations by the PDRC who accuse the caretaker government and cabinet ministers of abusing authority and widespread corruption.
Several thousand UDD members also joined red-shirt leader Jatuporn Prompan in Chiang Mai province to show their support for the Feb 2 election.
Mr Jatuporn predicted that the PDRC's shutdown campaign will last no more than a week since people in Bangkok will start running out of patience with the prolonged rallies.