The red-shirt United Front for Democracy against Dictatorship (UDD) plans to pressure the ruling Pheu Thai Party to further challenge the Constitution Court by calling for a third reading vote in parliament to amend Section 291 of the charter.
The move comes after the UDD on Wednesday rejected the court judgement to veto the charter amendment draft to create a fully elected Senate.
The third reading vote on amending Section 291 is pending following an earlier charter court ruling on July 13 last year that such a change could not go ahead without there being a public referendum.
However, the red shirts also said Wednesday they would end their rally at Rajamangala National Stadium.
UDD core leader Jatuporn Prompan told about 30,000 demonstrators at the stadium, as estimated by Bangkok Post reporters, to "go home to prepare for the new battle".
He asked UDD supporters to get red shirts in their communities to back government MPs to vote for Section 291 which will allow the set-up of a charter drafting committee to rewrite the whole constitution.
"Since we can't change it section by section, we will change the whole charter," Mr Jatuporn said.
"We have yet to achieve the goal of getting real democracy and justice even though almost 100 of us died and 2,000 were injured," he said, referring to the red-shirt protests in 2010.
"We must move further to seek democracy even if we have to die."
Deputy Commerce Minister and UDD core leader Nattawut Saikuar told the crowd at the stadium: "The first round of fighting is over; we are now moving into the next fight between democratic powers and off-system powers."
"Our hope for charter amendment is over but that of Mr Suthep [Thaugsuban, leader of the anti-government rally at Democracy Monument] to reap political benefits from Pheu Thai being dissolved is over as well," he said.