Thai protesters briefly stormed into army headquarters in Bangkok in a bid to get the military to join their efforts to topple the government of Prime Minister Yingluck Shinawatra.
More than 1,000 opposition supporters left the compound peacefully Friday after about two hours.
Army Commander General Prayuth Chan-ocha later urged protesters not to force the army to take sides.
Opposition leaders say Sunday will be their "victory day" and have called for supporters to besiege the prime minister's office. They vow to take over every ministry until Prime Minister Yingluck resigns.
She survived a no-confidence vote in parliament on Thursday. The prime minister refuses to step down and has called for dialogue to resolve the situation. She vows not to use violence to stop the protests.
The protesters have taken over parts of the finance and foreign ministries and surrounded the interior ministry. On Thursday they pulled down electrical cables outside police headquarters and an adjacent hospital, forcing them to use backup power.
The street protests are the largest in Thailand since 2010, when more than 90 people were killed in a military crackdown on an opposition protest.
The latest demonstrations were triggered several weeks ago by an amnesty bill that would have allowed former Prime Minister Thaksin Shinawatra, Ms. Yingluck's brother, to return home and avoid a two-year jail term for corruption. The Senate rejected the bill, but protests have continued.
Prime Minister Yingluck was elected in 2011. Her brother was toppled by a military coup in 2006 and later convicted of corruption. He has lived in exile to escape the charges, which he says were politically motivated.