President Trump has revealed uncertainty about who will take over Iran, as many of the likely front-runners were killed in initial strikes.

"The attack was so successful it knocked out most of the candidates," Trump told ABC’s Jonathan Karl.

"It's not going to be anybody that we were thinking of because they are all dead. Second or third place is dead."

Karl, who posted a summary of the exchange on X and also discussed it on-air, said it was “striking how stunningly successful the president believes this military operation has been.”

Trump earlier told Fox News on Sunday that 48 Iranian leaders were killed in the strikes by the U.S. and Israel, which decapitated much of the nation’s leadership.

The president did not specify which of those leaders the U.S. believed may have been front-runners to take over from Ayatollah Ali Khamenei, who was also killed in the strikes, but among the dead are Ali Shamkhani, one of his top advisers; General Mohammad Pakpour, commander of the Revolutionary Guards; and Mahmoud Ahmadinejad, the hardline former president.

During a transition period following Khamenei’s death, Iran will be led by a temporary council comprising the president, Masoud Pezeshkian; Gholam-Hossein Mohseni Ejei, the head of the judiciary; and senior cleric Alireza Arafi.

Iran has taken a defiant tone as the American and Israeli airstrikes continued, and top Iranian security official Ali Larijani vowed on X that "we will not negotiate with the United States."

But Trump contradicted that in his interview with ABC, describing how he had received overtures from those eager to make peace.

“He told me that somebody within the Iranian government has reached out to him,” Karl recounted.

“I asked him who it was, and he said ‘I probably shouldn’t tell you, but it was somebody who had survived,’ and somebody who he added was no longer reporting to the supreme leader.”

Meanwhile, Trump has suggested the conflict with Iran could last for the next four weeks, The Daily Mail reports.

"It's always been a four-week process. We figured it will be four weeks or so. It's always been about a four-week process so - as strong as it is, it's a big country, it'll take four weeks - or less," Trump said.

Trump added that he remained open to more talks with the Iranians, but did not say if that would happen "soon.”

"I don't know," Trump said, according to the report. "They want to talk, but I said you should have talked last week, not this week," he added.

In a video posted on Truth Social, Trump warned that three U.S. service members had been killed and said there would likely be more American casualties.

“He was quite candid,” said Karl, recounting how Trump had addressed those casualties in his interview with ABC.

“He said it’s war, and there are casualties in war. He also marveled at the fact that he’s now been through three significant military operations. The first one in Iran, the operation to take out Maduro, and now this one in Iran. And he said we have three casualties, three casualties. The Iranians, he said, can’t count how many they’ve had.”

Possible contenders to be Iran’s new supreme leader include Mojtaba Khamenei, Khamenei’s second son; Alireza Arafi, the cleric who is serving on the temporary council; Mohammad Mehdi Mirbagheri, a hard-line cleric critical of the West; and judiciary head Gholam-Hossein Mohseni Ejei, also serving on the temporary council.

Another potential candidate is Hassan Khomeini, the grandson of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini, who is widely seen as a reformist with moderate views.