Thai Prime Minister Yingluck Shinawatra arrived at the Constitutional Court on Tuesday to defend herself against charges of abuse of power, one of two legal challenges that could see her removed from office this month.
Six months of street protests aimed at toppling Yingluck have undermined her government, but she has clung on and the number of protesters has dwindled.
However, tension is rising again, with her supporters threatening action if the courts remove her and fears of confrontation with the protesters growing.
Both her supporters and the anti-government protesters plan large rallies in or around Bangkok next week.
Yingluck is charged with abuse of power over her transfer of National Security Council chief Thawil Pliensri in 2011, which opponents say was designed to benefit her Puea Thai Party. If found guilty, Yingluck could be forced to step down and some legal experts say her entire government would have to go too.
A verdict will not be handed down on Tuesday but could come quickly afterwards.
Amongst the other charges Yingluck faces is one of dereliction of duty over a state rice-buying scheme that critics say is riddled with corruption and has run up huge losses.
These charges were brought by the National Anti-Corruption Commission, which is expected to deliver its ruling this month. If found guilty on this count, Yingluck could be removed from office and face a five-year ban from politics.
Efforts to end the protracted political crisis have come to nothing.
Proposals by opposition leader Abhisit Vejjajiva for the six-month delay of a general election planned for July, so as to allow time for political and electoral reforms, have been rejected by the Puea Thai Party and leaders of the anti-government movement.
Yingluck's cabinet is expected to discuss the election date on Tuesday and could draw up a draft decree for royal endorsement.
The protests since November form part of a long-running crisis that broadly pits Bangkok's middle class and royalist establishment against the mainly poor, rural supporters of Yingluck and her brother, ex-premier Thaksin Shinawatra.
Thaksin was ousted by the military in 2006 and now lives in exile to avoid a jail term handed down in 2008 for abuse of power. His opponents accuse him of corruption and nepotism.
(Additional reporting by Pracha Hariraksapitak; Editing by Alan Raybould and Clarence Fernandez)