Karami's earlier announcement that he would resign came after he was unable to form a new cabinet.
"I made a promise that if I reach a dead end, I will go back to the Ein Tineh gathering," Karami said on Wednesday, referring to pro-government factions.
"I have informed the president that after the Ein Tineh meeting, I will call his excellency to officially inform him of my decision to step down."
Karami's intention to bow out follows a deadlock over forming the government, which must be completed before parliamentary elections can be held.
Elections must be held before the 31 May expiry of the current legislature's mandate. The opposition - which is expected to win them - is eager to see them held on time.
In a slap to the opposition, pro-Syrian Presiden Emile Lahud brought back Karami to form a new government on 10 March.
Karami's appointment was seen
as Lahud's slap to the opposition
Karami sought to form a national unity government including opposition members because he maintained that conditions in the country required all parties to shoulder responsibility.
But critics said the move was intended to give legitimacy to a cabinet that would still be dominated by Syria's allies and that Karami was proposing it only to hold up the process and delay elections that the leadership fears it will lose.
If Karami does step down, he remains at the top of a caretaker cabinet indefinitely until a new government is in place.
But the business of forming a government goes back to square one.
The president will have to poll legislators on whom to appoint as prime minister designate, the nominee will have to conduct a new round of negotiations on the cabinet's composition, and the parliament will have to approve the government.
There is also the risk that Karami will not formally say he is bowing out, a move that would short-change the process of even designating a new premier.
The new government's priority will be to steer an electoral law through parliament and oversee the election process.
"It's clear they don't want a new cabinet
and they don't
Deputy parliament speaker Michel Murr said organising an election would take more than a month.
The anti-Syrian opposition has accused authorities of stalling, saying they want neither a new cabinet nor parliamentary elections.
"It's clear they don't want a new cabinet and they don't want elections," said prominent opposition member Nayla Muawad, wife of president Rene Muawad, who was slain in a 1989 car bombing.
She added that if Karami starts stalling, "he will be the loser".
Lebanon has been in political crisis since the 14 February assassination of former prime minister Rafiq al-Hariri.
His death in a bomb blast - which the opposition blamed on Syria and its allies in Lebanon - prompted protests that forced the government at the time, led by Karami, to resign on 28 February.