The gathering will be held at Hotel De Palma, Ampang, at 2.30pm.
Rafizi had announced his candidacy yesterday and is expected to take on incumbent deputy president Azmin Ali, who is the economic affairs minister.
Azmin has not yet declared whether he would defend the post or go for the presidency, where he would have to face PKR de facto leader Anwar Ibrahim.
The PKR elections are scheduled to take place from September through October.
Rafizi, who was unable to defend his Pandan MP seat in the recent general election because of a court conviction, described his bid for the party’s No. 2 post as a “heavy burden because I have no government post or money”.
“Defeat or victory is not a big deal to me, but I must bear the trust to defend the Reformasi ideals that gave birth to Keadilan (the precursor to PKR).
“I am not the best among the existing leaders.
“There are leaders older, greater, more mature and wiser than me.
“Just this once, however, I need to bear the burden of the trust that drives the Reformasi ideals after we succeeded in forming the government with other Pakatan Harapan comrades,” he said in a message to his supporters.
He said he had to rely on his friends at the party grassroots, whose lives had not changed before or after the general election.
“Neither has mine. I am only a Reformasi activist who wants to stay true to the idealism that spurred me to plunge into the political cauldron 20 years ago,” he said.
He said he hoped to meet as many of the PKR grassroots activists as possible in the coming weeks of the campaign.
“I am ready to listen, ready to be criticised, ready to seek forgiveness and ready to propose how we want to build this Reformasi party, based on our ideals,” he said.