A Democratic member of the Senate Foreign Relations Committee told reporters Tuesday that he is preparing a challenge to President-elect Donald J. Trump’s choice for Secretary of State, Exxon-Mobil CEO Rex W. Tillerson.

“It is my expectation that we will have thorough hearings into questions that are already being raised by both Republican and Democratic senators,” said Sen. Christopher A. Coons (D.-Del.), who is a graduate of Amherst College and both the Yale University law school and its school of divinity. The senator sat in a brown cushioned chair next to an unlit fireplace in the room just outside the Senate’s press gallery and took questions for 30 minutes in a format known as a “pen and pad.”

Although it has been the practice of Senate Foreign Relations Committee Chairman Sen. Robert P. Corker Jr. (R.-Tenn.) with nominations from President Barack Obama to only move forward when the committee is unanimous, Coons said there is no way the committee will be unanimous in support of Tillerson.

Coons said he would not be surprised if there are Republican votes against Tillerson in committee, as well.

Presidential nominees need a simple majority in the Senate for confirmation, but with the Republicans sitting with 52 votes, plus incoming vice-president Michael R. Pence to break a tie, three GOP defectors are enough to torpedo a nominee.

The senator said he has never met Tillerson, and he is aware that members of the so-called national security establishment such as former secretary of state Condoleeza Rice and former Pentagon chief Robert M. Gates have praised the oil man. Coons allowed he would take those endorsements under consideration.

Rice’s endorsement has special meaning inside the national security community, because although she came to prominence during the Global War on Terror, her education and training was as an expert on Russia–mentored by former secretary of state Madeleine Albright‘s father Josef Korbel.

The connection between Tillerson and Russia is crucial, Coon said.

“Mr. Tillerson has been for decades working at and most recently helping lead the world’s largest publicly traded oil and gas company and that certainly gives him a deep and broad experience,” the senator said. “There are real differences between negotiating an oil contract, an oil exploration drilling contract in the Arctic with Vladimir Putin, and standing up for, fighting for core American values.”

While President Barack Obama has at times opened the American sectors of the Arctic Ocean for oil exploration and at other times banned oil exploration there, the Russian government has had a more consistent and nurturing approach, with oil companies such as Exxon-Mobil drilling in its own corner of the Arctic Ocean and in western Siberia.

In 2013, Russian President Vladimir Putin inducted Tillerson into Russia’s Order of Friendship to mark the company’s energy investments in Russia. In 2014, Exxon-Mobil hit the largest oil deposit in the company’s history, estimated to be larger than the entire Gulf of Mexico. Later in 2014, President Barack Obama placed economic sanctions on Russia–in response to its aggression into Ukraine–that shut down Exxon-Mobil’s Russian operations before they really began to pay off.

This “friendship” between Tillerson and Putin has been joined with charges by Capitol Hill Democrats and Obama administration officials that actors under the control of but not part of the Russian government hacked into the email servers of the Democratic National Committee and the Republican National Committee. The narrative put forward is that because the actors associated with the Russian government only leaked emails damaging to the Democrats and the presidential campaign of their nominee Hillary R. Clinton, it must have been the intent of the Russian government to help Trump get elected and to hurt Clinton’s campaign.

Coons said he understands that there is no direct evidence that Russian government officials directed interference in the 2016 presidential campaign, and he does not know of a concrete effect this participation could have had on the election results.

That is why Congress has to investigate, he said.

After the House and Senate intelligence committees have conducted their own investigations, the Delaware senator said he expects the Republican leadership to establish a select committee to conduct a further and deeper investigation.

The senator said he was also concerned about the potential appointment of former ambassador to the United Nations John Bolton to serve as Tillerson’s deputy.

“Bolton is–my impression is–is an unreconstructed neo-con, who still believes the Iraq War was a great idea, despite all evidence to the contrary, whose views on Iran remain very hard line and who in combination with Tillerson will provide little restraint on a president-elect and a national security team that strike me as too heavily inclined towards the use of force, rather than diplomacy.”