Five things to watch in Rex Tillerson's Senate confirmation hearing

Sen. Barrasso on Tillerson: US should use energy as 'geopolitical weapon'

Former Exxon Mobil CEO Rex Tillerson's confirmation hearing to become the nation's top diplomat will be a highly contentious event, if statements from Democratic members of the Senate Foreign Relations Committee are any indication.

Most of the Democrats on the committee and one Republican — Sen. Marco Rubio — have said they have serious concerns about Tillerson's nomination. The other Republican committee members either praised Tillerson's business experience in brief comments or have not issued official statements on the pick.

The Wednesday hearing was always bound to be remarkable. Tillerson will be the first modern nominee for secretary of State who is better known as a businessman than a statesman or civil servant.

But Exxon's business ties to Russia have raised the hackles of many politicians in light of President-elect Donald Trump's denial until recently that Russia was behind cyberattacks on U.S. targets during the 2016 election and sought to undermine the U.S. democratic process.

The hearing gives lawmakers the opportunity to scrutinize the incoming president's foreign policy agenda. Even before entering office, Trump has upended long-standing diplomatic norms, and Democrats have been blunt when it comes to Trump's vision.

"I found many of President-elect Trump's foreign policy statements as a candidate, and now as the next president of the United States, to be disturbing at best and frightening at worst," said the committee's ranking Democrat, Ben Cardin of Maryland.

Here are the main themes to watch in Tillerson's confirmation hearing on Wednesday.

What is his relationship to Russia?

Some see Tillerson's nomination as part of Trump's efforts to forge a friendlier relationship with Russia, and many lawmakers on both sides of the aisle are deeply skeptical of that endeavor.

Exxon was in the process of helping Russia's state-owned Rosneft explore for oil and gas in the Arctic and other locations when the United States and European Union slapped Moscow with sanctions over its annexation of Crimea and its military interference in Ukraine.

Tillerson Talk: The words senators used in their initial statements

Tillerson opposed the sanctions and upset the White House by sending an Exxon executive to a Russian business forum last year. Democrats flagged those issues in public statements, and some have even questioned Tillerson's loyalty to the country.

"Mr. Tillerson has demonstrated he knows the corporate world and can put his shareholders' interests first, but can he be a respected secretary of State that puts the national security interests of the American people first? It remains to be seen," Cardin said last month.

Among Republicans, 2016 presidential contender Rubio, who sparred often with Trump on the campaign trail, has expressed the most explicit skepticism of Tillerson's suitability for the office, saying he has "serious concerns about his nomination."

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Both GOP and Democratic committee members have expressed support for hitting Russia with further penalties after revelations of its meddling in U.S. elections. Senators will likely press Tillerson on whether the incoming administration plans to roll back existing sanctions on Russia.

Where does he stand on climate change?

Tackling climate change has been a major push under the Obama administration. The Paris Agreement, an international deal to cut carbon emissions, has been one of Secretary of State John Kerry's signature achievements.

Exxon, the world's most valuable publicly traded energy company, has been accused of misleading the public on climate change, so the issue might seem like an easy target for Democrats. That might not be the case.

In recent years, Tillerson has led Exxon's shift toward acknowledging the effects of climate change and supporting a carbon tax to offset greenhouse gas emissions. Some say the move was motivated by public relations and a desire to front run environmental policy that could be even more detrimental to Exxon's business, but whatever the case, Tillerson will likely be prepared to tackle questions on climate change.

While many Democrats raised questions about Exxon's record on climate change after Tillerson's nomination — and are sure to do so on Wednesday — Sen. Tom Udall said he was "pleased" to learn about Tillerson's position after meeting with him last week. Still, the gulf between Tillerson and Trump's public position on climate change could present another line of attack.

"I'm encouraged that, contrary to the extreme statements by President-elect Trump, Mr. Tillerson believes in science and sees value in the United States remaining a party to the Paris Agreement," Udall said.

What is his take on Trump?

Some Democrats softened their language on Tillerson after meeting with him last week, but another theme emerged: Tillerson and Trump have differences on more than just climate change. Those difference may create flash points on Wednesday.

Sec. of State-designate Tillerson meets with Sen. Coons

Sen. Christopher Coons of Delaware told MSNBC's "Morning Joe" last week, "there is a real tension between his expressed views in our conversation yesterday and the views of President-elect Trump, so I look forward to exploring that tension further in the upcoming confirmation hearings."

Udall expressed concern last week about whether the Trump team is on the same page.

In a statement Udall said, "While I was impressed by Mr. Tillerson's direct answers to my questions, he was unable to clarify what President-elect Trump's policies and positions will be."

Does he have the right experience?

A number of Democrats have questioned whether the lifelong oilman's experience negotiating energy deals qualifies him to serve as the nation's top diplomat.

"Having no practical experience in diplomacy, Mr. Tillerson has no proven knowledge or regard for the norms and necessities that so much of our modern diplomatic and security efforts depend upon," Democratic Sen. Bob Menendez of New Jersey said last month.

Rep. Hoyer: Trump's cabinet picks lack critical experience

It's also possible Democrats will try to trip up Tillerson with questions they believe are beyond his realm of expertise, but they may be surprised by the depth of his knowledge. Energy experts recently told The New York Times that Tillerson is well-versed in the affairs of a handful of countries.

Still, Tillerson will likely be confronted with a range of questions on hot-button issues, including the Iran nuclear agreement, the Syrian civil war and the Israeli-Palestinian peace process.

What is America's role in the world?

Trump has advocated a U.S. foreign policy that is wary of overseas entanglements. He has also raised the prospect of pulling out of NATO — the military backbone of the Western world for almost 75 years — if treaty members do not contribute more to its funding.

That plays well with libertarian-leaning Republican Sen. Rand Paul, who has said he will keep an open mind on Tillerson. Paul publicly criticized John Bolton and Rudy Giuliani, two early considerations for secretary of State, as being too hawkish.

Tillerson will have to square Trump's vision with the more hawkish views of some Republican committee members and bipartisan support for NATO.

One day after Trump announced Tillerson as his pick, Rubio and Democratic Sen. Edward Markey wrote a letter to Trump "calling on him to strengthen our system of alliances, including NATO and the U.S.-Japan Mutual Security Treaty, and long-standing nuclear nonproliferation policies."

— CNBC's John Schoen contributed to this story.