Donald Trump has questioned plans by the Chinese tech firm ByteDance to keep a majority stake in TikTok’s US operations as part of a “trusted technology deal” with Oracle.

“Conceptually I can tell you that I don’t like that,” Trump told a news conference when asked about a reported proposal to give Oracle only a minority share. “I’m not prepared to sign off on anything. They’re going to be reporting to me tomorrow morning and I’ll let you know.”

Trump said he would be briefed on Thursday about a proposal that calls for Oracle to become a “trusted technology provider” for TikTok’s American operations, but he did not favour the idea of having the Chinese firm retain control.

“It has to be 100% as far as national security is concerned,” Trump said. “I have to see the deal.”

The president also expressed surprise that Washington could not demand payment from the companies in exchange for approving any agreement. “Amazingly I find that you’re not allowed to do that,” he said. “What kind of a thing is this?”

Trump’s intervention followed six Republican senators urging the administration to reject the TikTok deal as long as ties remained to Chinese owner ByteDance and suggesting the president could block the proposal.

Trump had previously threatened to ban the app unless its US operations were sold to a US company and the US government received a share of the proceeds.

Marco Rubio, the first senator to call on the administration to investigate TikTok over censorship concerns, cited “serious questions” about Oracle’s role, the technology it would provide to ByteDance and the future of the application’s algorithm in a letter to Trump.

“We remain opposed to any deal that would allow China-based or controlled entities to retain, control or modify the code or algorithms that operate any US-based version of TikTok,” he wrote.

“We are heartened that this deal still requires government approval, and if reports indicating this proposed deal will retain links to ByteDance or other Chinese-controlled entities, we strongly urge the administration to reject such a proposal on national security grounds.”

Senator Ted Cruz sent a separate letter to Trump arguing that the Oracle ByteDance deal “failed to meet the intent of the president’s executive orders” and “raises serious national security concerns”.

The White House press secretary, Kayleigh McEnany, earlier told reporters a decision would be made “in short order”. The White House economic adviser Larry Kudlow said security and the ownership question were of paramount concern.

US national security officials fear that ByteDance could provide American user data to the Chinese government. But Trump may not want to alienate 100 million-odd American TikTok users so close to the 3 November elections.

Trump has also said he is a fan of Oracle’s co-founder and chairman, Larry Ellison, one of few tech executives to openly support him.

Meanwhile China has updated its export control rules to give it a say over the transfer of technology, such as TikTok’s recommendation algorithm, to a foreign buyer. Chinese officials have said ByteDance should not be coerced by the United States into a deal.