President-elect Donald Trump has chosen ExxonMobil CEO Rex Tillerson to serve as secretary of state, the transition team announced Tuesday, setting up a heated Senate confirmation battle and signaling a desire to ease Washington’s estrangement with Russia.

Like Trump, Tillerson, 64, has no formal foreign policy experience, but has built close relationships with many world leaders by closing massive deals across Eurasia and the Middle East on behalf of the world’s largest energy company.

“His tenacity, broad experience and deep understanding of geopolitics make him an excellent choice for Secretary of State,” Trump said in the statement.

Tillerson was originally a dark horse for the secretary of state nomination, but emerged from a lengthy public interview and vetting process that included better-known quantities like former New York Mayor Rudy Giuliani, 2012 GOP nominee Mitt Romney and Sen. Bob Corker, chairman of the Senate Foreign Relations committee.

Romney confirmed he was not the pick in a Facebook post Monday night, and Trump tweeted that he will announce his pick Tuesday morning.

Trump has called Tillerson a “world-class player” and the transition team is likely to stress that his mastery of complex negotiations and knowledge of geopolitical factors shaping the oil industry are directly relevant to heading US diplomacy and managing the State Department.

Tillerson was recommended to Trump by former secretaries of state Condoleezza Rice and James Baker and former Secretary of Defense Bob Gates, sources told CNN.

Trump and Tillerson possess similar dealmaking business backgrounds and similar views of the world, sources said, and there was a level of comfort that Trump hadn’t found with anyone else.

Trump’s decision to press ahead with the Tillerson nomination could ignite the first big showdown between the new White House and Capitol Hill and set a benchmark for Republicans worried about the direction of the President-elect’s own foreign policy. It will also embolden Democrats who see Tillerson as perhaps the most vulnerable Trump Cabinet appointee to a bruising Senate confirmation battle.

One Trump official told CNN there’s a plan to sell Tillerson to skeptical senators and the transition team believes the more lawmakers get to know him, the more comfortable they will be.

Republican hawks such as Sens. John McCain and Marco Rubio are deeply perturbed by the close relationship Tillerson forged with Russian President Vladimir Putin. They fear Trump and Tillerson would bring US policy far more in line with Russia, which is locked in the worst confrontation with Washington since the Cold War and is seeking to again become a great power rival to the United States.

Tillerson, a multi-millionaire, he will be an easy fit in the roughly one-third of Trump’s emerging Cabinet which is made up of corporate titans and wealthy Wall Street players. He is also another down-payment by the President-elect to tear down the political establishment in Washington and to replace the inhabitants of what he has called a “swamp” with new blood and potential cabinet secretaries with real world experience.

But in order to be confirmed, Tillerson must satisfy senators that there is more to him than a businessman eyeing a new challenge in statesmanship.

Not much is known, for instance, about his personal views on international relations as distinct from the positions of his company.

His views on the alliances like NATO and in Asia that have sustained American power and global security since World War II — on which Trump cast doubt during the presidential campaign — are largely unknown.

He will have to explain why his own lack of formal foreign policy experience is not a disqualifying feature of his resume. After all, negotiating is just one aspect of the job of secretary of state. The top US diplomat must also frame a coherent foreign policy doctrine for the United States, exemplify its values, have a deep grounding in history and understand the complicated motivations of its international partners and adversaries.

The confirmation hearing would also force Tillerson to develop positions on issues ranging from global warming to North Korea’s nuclear program and US humanitarian aid in the developing world.

Order of friendship from Putin

Tillerson developed his close ties with Putin as he negotiated a deal with Russian oil giant Rosneft to provide access to lucrative oil resources in the Arctic. The agreement will be at the center of his confirmation hearing.

For his efforts, Putin awarded Tillerson Russia’s prestigious Order of Friendship in 2013. The deal has so far not yielded its promise.

Exxon was hit hard by a round of US and European Union sanctions that targeted Russia in 2014 for its intervention in Ukraine. Exxon said it could have lost up to $1 billion due to the sanctions, according to regulatory filings.

The sanctions issue will provide ammunition for Democratic senators keen to probe apparent glaring conflicts of interests across the nascent Trump administration.

Even if Tillerson were to sever all links and investments related to ExxonMobil, action he took as secretary of state — for instance, advocating the lifting of sanctions against Russia over its annexation of Ukraine — could clearly benefit the firm and his former industry.

Experience at ExxonMobil

Tillerson, a native of Wichita Falls, Texas, has worked for ExxonMobil for 40 years after joining the firm as a production engineer and has steered the giant global firm since 2006.

Through the end of 2015, he had made more than $240 million as CEO, according to an analysis from board and executive data provider Equilar.

That total includes his base salary, bonuses, stock awards and other compensation over 10 years.

His nomination will be greeted with dismay by climate activists and environmentalists who will see it as tantamount to a takeover of US foreign policy by Big Oil.

But he worked to somewhat soften ExxonMobil’s stance on climate change since. When he took over in 2006, the company was struggling with how to balance its corporate interests with a growing public consensus on global warming, according to Steven Coll’s book “Private Empire: ExxonMobil and American Power.”

Under the previous CEO Lee Raymond, ExxonMobil promoted skepticism about the science of climate change. But Tillerson quietly adjusted the company’s position on the issue, according to Coll.

“Greenhouse gas emissions could prove to be significant,” Tillerson said in a speech to the Council on Foreign Relations in 2007. “So it has been ExxonMobil’s view for some time that it is prudent to take action while accommodating the uncertainties that remain.”