Thai opposition demonstrators have besieged the seat of government in defiance of authorities who have vowed to reclaim the zone this week so Prime Minister Yingluck Shinawatra can return to work at her headquarters.
The government is trying to seize back key official buildings after more than three months of mass rallies seeking to topple Yingluck's administration and curb the political domination of her family.
Yingluck has been unable to use Government House for about two months and has instead held meetings in various locations across the capital.
Protesters have taunted her for overseeing a mobile government, which they are hoping to upend through a combination of street action and pressure through Thailand's notoriously interventionist courts.
Thousands of demonstrators, among them a hardcore group known as the Student and People Network to Reform Thailand, rallied near Government House on Monday.
Protesters poured buckets of cement onto a sandbag wall in front of a gate to Government House.
"We will not let them (the government) come back to work because we do not want them," firebrand protest leader Suthep Thaugsuban said from a stage.
"Yingluck will never have a chance to work at the Government House again."
On Friday, riot police swept through barricades around Government House with little resistance, clearing tents and sandbags from the area.
That operation marked an unexpected shift in tactics after months during which the demonstrators have often appeared to be more in control of the city than the authorities.
But hours later, protesters had returned and rebuilt their barricades unopposed.
As they try to clear the protests, authorities are determined to avoid confrontation with the demonstrators, whose numbers have dwindled from highs of at least tens of thousands following widely disrupted February 2 elections.
Labour Minister Chalerm Yubamrung said police would take "soft measures" to reclaim five official sites this week - including Government House - vowing to negotiate with protesters rather than "crack down".
