Washington CNN  — 

Sen. Marco Rubio said Sunday that Treasury Secretary Steven Mnuchin should not attend an upcoming investment conference in Saudi Arabia amid an ongoing investigation into the country’s possible involvement in the disappearance of Saudi journalist Jamal Khashoggi, who went missing earlier this month in Turkey.

“I don’t think he should go,” Rubio told CNN’s Jake Tapper on “State of the Union,” adding that he doesn’t think any US officials should continue with their usual business in Saudi Arabia until Washington gets to the bottom of Khashoggi’s disappearance.

“I don’t think any of our government officials should be going and pretending it’s business as usual until we know exactly what’s happened here,” Rubio, R-Florida, said.

Khashoggi, a columnist for The Washington Post, went into the Saudi consulate in Istanbul on October 2 to obtain paperwork that would allow him to marry his Turkish fiancée. He hasn’t been seen in public since.

Rubio said that there will be “a very strong congressional response” if Khashoggi is found dead.

“I believe the Trump administration will do something — the President has said that. But if he doesn’t, Congress will.” Rubio told Tapper.

“That I can tell you with 100 percent certainty, with almost full unanimity across the board, Republicans and Democrats, there will be a very strong congressional response if in fact the Saudis lured him into that consulate, murdered him, cut up his body and disposed of it,” he said.

Saudi Arabia firmly denies any involvement in Khashoggi’s disappearance and says he left the consulate that afternoon. But his fiancée, Hatice Cengiz, who was waiting outside the consulate, says she did not see him re-emerge. Turkey has called on Saudi officials to provide evidence he left the consulate.

President Donald Trump vowed in a “60 Minutes” interview that airs Sunday that the United States would get to the bottom of what happened to Khashoggi and that there would be “severe punishment” if he is found to have been killed.

Mnuchin remains committed to event despite sponsor pullouts

Mnuchin said Friday that he still plans to attend the investment conference, doubling down on the administration’s hesitant response to Khashoggi’s disappearance.

“The conference is on. For now, I am going,” Mnuchin told reporters early Saturday morning at a closing press conference at the International Monetary Fund’s annual meeting.

He said administration officials were looking forward to the results of the investigations and suggested plans could changed based on what information comes out next week.

Even as Mnuchin remains committed to attending the conference in Riyadh, Saudi Arabia is facing growing isolation as sponsors pull out of the event, which is slated to take place later this month.

Most of the news outlets that had agreed to sponsor the Saudi Future Investment Initiative – known as “Davos in the desert” – have now withdrawn.

They include Japanese media company Nikkei, CNBC, The New York Times and the Financial Times. Bloomberg said Friday it was pulling out as a media partner but added it still planned to cover news from the conference.

CNN, which was a media partner for the event, confirmed Friday that it too would no longer participate in the conference. Viacom CEO Bob Bakish, Uber chief Dara Khosrowshahi and The Economist’s editor-in-chief, Zanny Minton Beddoes, have also pulled out.

However, International Monetary Fund chief Christine Lagarde told reporters Saturday at the IMF’s annual meeting in Indonesia she still planned to go but would be paying close attention to new information about Khashoggi’s disappearance.

CNN’s Donna Borak contributed to this report.