Prabowo refused to acknowledge the result of the presidential election accusing the KPU of being unfair.
KPU declared rival candidate Joko Widodo as president elect after the recapitulation of votes on Tuesday night.
Chairman of the Prabowo-Hattas team of lawyers Firman Wijaya said the team had prepared evidence to back up the suit to be used by the Constitutional Court.
"We will file the suit tomorrow. We have silent evidence in the form of data and speaking evidence in testimony," Firman said here on Thursday.
He said the team is waiting for the KPU to hand over the recapitulation of the result of the presidential election.
The team needs the recapitulation to file the suit, "but until now the KPU has not sent the document to us," he said.
He warned KPU to immediately send the document otherwise it could be considered to have failed in carrying out its constitutional duty.
He said filing the law suit with the Constitutional Court is not the only judicial procedure to be followed.
He said he did nor rule out taking other judicial procedure to deal with other criminal case.(*)