Wickremesinghe, who has served as prime minister six times, succeeded Gotabaya Rajapaksa, who left Sri Lanka and resigned from office last week in the wake of widespread protests against his management of the country's economy. On July 21, there was a swearing-in ceremony held in parliament.
According to the sources close to Wickremesinghe and Gunewardena, he is anticipated to name Dinesh Gunewardena, a former foreign and education minister, as prime minister together with a new government on July 22.
The 73-year-old veteran politician, who was overwhelmingly elected as head of state in a parliamentary vote Wednesday, took his oath of office with the country's police chief and top military brass standing behind him.
Official sources said the new leader was expected to shortly form a cabinet featuring several opposition lawmakers to steer the country out of its worst economic crisis since gaining independence from Britain.
Opposition leader Sajith Premadasa, who supported a rival candidate in Wednesday's vote, said he had met with Wickremesinghe to discuss how to protect the country from further "misery and disaster".
"We as an opposition will provide our constructive support for efforts to alleviate human suffering," Premadasa tweeted Thursday.
A foreign exchange crisis triggered by the coronavirus pandemic and exacerbated by mismanagement has left Sri Lanka suffering lengthy power blackouts and record-high inflation.
The country's 22 million people have also endured months of food, fuel and medicine shortages.
Public anger boiled over when tens of thousands of protesters stormed the home of then-president Gotabaya Rajapaksa, forcing him to step down.
Wickremesinghe has been tainted in the eyes of many Sri Lankans by his association with Rajapaksa, whose political party backed the new president's ascent.
"We don't need Ranil, he is the same as Gota," said Irfan Hussain, a poultry farmer in the capital Colombo.
"I don't think he is going to make our country better," he added. "He only thinks about himself, not the people."
(With agency inputs)