Thousands of anti-government protesters took to the streets of Bangkok Saturday demanding political reforms before the next general election is held.

Suthep Thaugsuban, a former deputy prime minister who now heads the People’s Democratic Reform Committee (PDRC), led supporters from their base at Lumpini Park in central Bangkok toward the Royal Plaza, near Parliament.

“We want to show the government that the people don’t want them anymore,” Mr. Suthep said. “We don’t expect today’s march to affect the government, but we want them to know the people have had enough.” The protests against the government of caretaker Prime Minister Yingluck Shinawatra began in early November to force her and her Cabinet to resign, after it attempted to ram through a general amnesty that would have benefited her fugitive elder brother.

The movement’s main goal is to oust what they call the “Thaksin regime,” a reference to former prime minister Thaksin Shinawatra, a populist politician who has dominated Thai politics for more than a decade, including from his self-exile to avoid a prison sentence.

Mr. Suthep, a former secretary general of the opposition Democrat Party, resigned his parliament seat to lead the demonstrations in the hope of forcing reforms before any new election.

Mr. Thaksin-led parties have won every general election since 2001, and would have won the snap polls held on February 2 but the voting was annulled by a Constitutional Court ruling on March 21.

That election was disrupted by protesters, rendering the outcome incomplete. A new date has not yet been set.

Mr. Suthep has vowed to disrupt future polls unless his demands for reforms are first met.

The PDRC, which at its peak drew hundreds of thousands in Bangkok, has seen a steady attrition of followers since violent attacks on its rallies last month that killed 12 people including four children.