The ongoing unrest in Thailand looks likely to continue in the coming months, with anti-government protesters demanding that Thai Prime Minister Yingluck Shinawatra step down before elections she has called for Feb 2, according to observers.

Tens of thousands of protesters marched through Bangkok again on Sunday, rejecting a national poll Yingluck has called in a bid to defuse the country's deepening political crisis.

The rally came a day after Thailand's main opposition Democrat Party announced it will boycott the elections, a move that appeared to embolden the protest movement.

The protesters split into more than a dozen groups scattered around central Bangkok, including some of the capital's main shopping areas.

One of the groups gathered outside Yingluck's home, but she was not there at the time.

Many protesters near the residence were women, while hundreds of transgender people also joined the protest. Hundreds of riot police blocked the crowd from moving past the home's outside gate.

Yingluck was in the northeastern provinces on an inspection tour. On Sunday morning, she traveled by train from Udon Thani to Nong Khai, considered the home of her Red Shirt supporters. She received a warm welcome at the Udon Thani railway station.

Yingluck admitted that she was worried about the situation outside her home, but because her family was not there, she said she believed nothing serious would happen, media said.

Earlier in the morning, Yingluck said it was a pity that the Democrat Party had decided to boycott the elections.

Sunday's rally also came a day before the Election Commission opens party registration for the upcoming elections. The registration is scheduled to take place at a Bangkok stadium, but there are concerns that protesters will block candidates from entering.

In the past two months, the demands of protest leader Suthep Thaugsuban and his protesters have changed repeatedly.

The demonstrators initially demanded, successfully, that the government vote down an amnesty bill that would have allowed Yingluck's exiled brother, former prime minister Thaksin Shinawatra to return to the country. After protesters then sought to overthrow Yingluck's government, she dissolved Parliament in early December.

Demonstrators now are demanding that Yingluck postpone the election and resign from the caretaker government.

Pitch Pongsawat, a scholar at the Chulalongkorn University in Bangkok, said that as each of the protesters' demands are met, they have become increasingly encouraged.

"The opposition party is likely to question the legitimacy of the election results as a way to challenge the ruling party, as was the case in 2006," he said.

Pongsawat also said the upcoming election is unlikely to end the unrest in Thailand.

Song Qingrun, a researcher at the China Institutes of Contemporary International Relations, said no basic agreements on reforms have been reached by the pro-government and anti-government groups, so the situation could get even worse.

"The two parties are unwilling to negotiate to reach basic agreements. The Thai political sphere and social society are falling apart," Song said.

Contact the writer at zhaoyanrong@chinadaily.com.cn

AP contributed to this story.