As lawmakers respond to Saudi Arabia over the disappearance and suspected murder of Washington Post columnist Jamal Khashoggi, Sen. Lindsey Graham is channeling his longtime friend, the late Arizona Sen. John McCain.

"This is about universal values. This is about defining who we are and what we will accept as a nation," Graham told reporters at the Capitol on Thursday.

"The one thing I've learned from John McCain above all else is that, in moments like this, you have to embrace your values," said Graham, R-S.C. "No more transactional interactions."

Graham, who is a close confidant of President Donald Trump, also said he was disappointed about his exchange yesterday afternoon with the Saudi Arabian ambassador to the U.S.

"It was not a very helpful phone call," he said, without offering more details.

The Trump administration has yet to appoint a U.S. envoy to the Saudi kingdom, instead positioning White House senior advisor and Trump's son-in-law Jared Kushner in a leading role for U.S.-Middle East relations.

A senior Turkish official told The New York Times that Khashoggi was murdered in the Saudi consulate in Istanbul, Turkey. But Saudi Arabia insists that Khashoggi left the consulate shortly after he arrived.

The Washington Post reported Wednesday that Saudi Crown Prince Mohammed bin Salman had ordered for Khashoggi, who was living in self-imposed exile in Virginia, to be coaxed back into the kingdom and detained.

Khashoggi, a Saudi journalist who had been a vocal critic of the kingdom's royal family, entered the consulate in Turkey on Oct. 2 and has not been seen outside it since, the Post reported.

Graham, the chair of the subcommittee on appropriations handling U.S. foreign assistance, was one of several senators to submit a letter to Trump on Wednesday evening that requires the administration to investigate Khashoggi's disappearance.

Under the Global Magnitsky Act, signed by President Barack Obama in 2012, the letter triggered a 120-day countdown clock for Trump to decide whether to impose sanctions on Saudi Arabia.

The letter was co-authored by Senate Foreign Relations Committee Chairman Bob Corker, R-Tenn., as well as the committee's ranking Democrat, Bob Menendez of New Jersey, and Vermont Democrat Sen. Patrick Leahy. Eighteen other senators of both political parties co-signed the letter to Trump.

At the White House on Thursday, however, Trump appeared to push back on the possibility of stifling investment opportunities between the U.S. and Saudi Arabia. Trump told reporters that there are other ways of handling the situation with Khashoggi, though it was not immediately clear what those alternatives could be.

Graham suggested Thursday that the Magnitsky investigation was the "first step" and could potentially be followed by "standalone legislation."

There is "a lot of interest in sending a strong signal," Graham added.

Neither the White House nor a spokesman for Graham immediately responded to CNBC's requests for comment.