Thailand's Senate was due to meet on Tuesday to try to find a solution to protracted political turmoil, with both sides putting pressure on the only legislative assembly still operating in the polarised country.
The deadlock, the result of anti-government protests that began in November, has largely crippled government, threatens to tip Thailand into recession and has even raised fears of civil war.
Last week the Constitutional Court ousted Prime Minister Yingluck Shinawatra and nine of her cabinet ministers for abuse of power, but her caretaker government has remained in office, clinging to hope for a July 20 election which would probably see its returned to power.
The crisis is the latest phase in nearly 10 years of rivalry between the royalist establishment and Yingluck's brother, former Prime Minister Thaksin Shinawatra, who was deposed by the army in a 2006 coup.
With the military declining to get involved this time, the anti-government side has called on the Senate to step in and force what is left of Yingluck's adminstration to stand down.
The upper house met on Monday to try to draft a "road map" but came to no conclusions. It will met again on Tuesday.
"We will stay here until we get a solution from the Senate about a way to end the country's crisis," Suthep Thaugsuban, leader of the anti-government protests, told his supporters outside parliament late on Monday.
Yingluck dissolved the lower house, the House of Representatives, in December for an election but the royalist opposition boycotted the vote and their activists disrupted it. It was later declared void.
The anti-government protesters are backed by the establishment which has long seen Thaksin as a threat. The former telecommunications tycoon won huge support in the rural north and northeast with populist policies despite authoritarian tendencies and accusations of corruption.
Thaksin lives in exile to avoid jail for a 2008 graft conviction but exerts extensive influence on the government from abroad.
The protesters want the remnants of Yingluck's administration replaced with a "neutral" interim prime minister who they want to draft reforms aimed at disabling Thaksin's political juggernaut, which has won every election since 2001.
The government says its removal would be unconstitutional and that it still has a mandate and is focussing on confirming the election date. Its "red shirt" supporters have warned of violence if the Senate throws the government out.
Caretaker Prime Minister Niwatthamrong Boonsongphaisan said on Monday he was hopeful that February's annulled election could be re-run soon and the government would meet the Election Commission on Wednesday to decide on the best date.
Rival supporters are staging sit-in protests this week and, although their main protest sites are far apart, fears of violence are growing. Twenty-five people have been killed since this round of protests began.
The military, which has intervened frequently in politics in the past, has remained aloof despite calls from some pro-establishment forces for it to oust the pro-Thaksin government.
The military says it is up to politicians to resolve political disputes.
(Additional reporting by Apornraath Phoonphongphiphat; Editing by Alex Richardson)