Timothy Stafford is a Research Fellow with Pacific Forum-CSIS, and a former Parliamentary Researcher to Sir Malcolm Rifkind.

To say that Rex Tillerson does not fit the standard profile of a Secretary of State nominee is to put it mildly. Between them, the last ten secretaries have at one stage or another filled the following positions prior to taking up the position: Senator, National Security Advisor, Chairman of the Joint Chiefs of Staff, UN Ambassador, Treasury Secretary, White House Chief of Staff, Deputy Secretary of State, and Supreme Allied Commander Europe. Tillerson, by contrast, is a career oil man with no experience of government work, let alone the diplomatic service.

What then, explains his selection?

Writing in the Los Angeles Times eight years ago, former Secretary of State James Baker outlined the primary quality any Secretary of State needs in order to be effective: “You cannot be successful unless you…have a clear understanding with the president that you are his principal foreign policy spokesman, formulator and implementer. There cannot be discordant voices on foreign policy. If there are, you will send mixed signals to other countries that will result in your administration being ineffectual. In public, a Secretary of State should be as close to a clone of the president as possible”.

For Donald Trump, finding someone who met that criterion was an uphill battle. All the names floated during the transition process – former Presidential candidate Mitt Romney, former New York Mayor Rudolph Giuliani, former CIA Director David Petraeus and Senate Foreign Relations Chairman Bob Corker – were household names in political circles. Yet none could ever have hoped to be seen as a true Trump confidante internationally. Had any one of those four been nominated, foreign governments would have held out hopes of turn the incoming Secretary into their envoy to Trump, rather than Trump’s envoy to them.

In the CEO of ExxonMobil, Trump appears to have found a chief diplomat with whom he sees eye-to-eye. Much like himself, Tillerson hails directly from corporate America. He is well placed to lead a re-prioritization of US foreign policy, away from human rights, democracy-promotion, and maintenance of a liberal world order, in favour of a narrow focus on advancing America’s economic wellbeing. Crucially, Tillerson’s commercial experience in Russia suggests that he will be comfortable pioneering Trump’s efforts to mend relations with Moscow, something that is anathema to almost every major player in the Republican foreign policy establishment. As far as unity within the administration is concerned, so far so good.

The immediate problem for the nascent Trump administration, is that the nomination will aggravate burgeoning tensions with Congress. Tillerson, like the President he hopes to serve, lacks any major constituency in Washington. The businessman’s willingness to establish comfortable relations with autocratic regimes, part of the rough and tumble of energy politics, will not play well with the Republican foreign policy hawks in the Senate.

Lindsey Graham, John McCain, and Marco Rubio in particular, are likely to make the his personally warm relationship with Vladimir Putin a central feature of his confirmation hearings. Moreover, Senator Rand Paul has already pledged do his utmost to block the appointment of John Bolton as Deputy Secretary – a move calculated to ease Republican concerns about Tillerson’s lack of diplomatic experience and mercantilist instincts.

The problems are likely to be even worse amongst Democrats. For them, the pick will – in the words of author Steve Coll – “confirm the assumption of many people around the world that American power is best understood as a raw, neocolonial exercise in securing resources”. As a result, the nomination for Secretary of State goes to Capitol Hill with a significantly higher chance of being rejected than any other in living memory.

Much may depend on former Bush-era grandees to carry the day. Former Secretaries of State and Defense Condoleezza Rice and Robert Gates have already praised the selection, and James Baker himself has emerged as a key supporter of his fellow Texan. It is possible that their gravitas will succeed in allaying Republican fears of a pro-Russian turn in foreign policy, encompassing the lifting of Ukraine-related economic sanctions, reduced support for NATO allies, and de facto support for Russian military policy in the Middle East. Tillerson, clearly a man of significant talent, may also exceed expectations when placed under scrutiny. Yet the margin for error is slender. Republicans hold 52 seats in the Senate. Trump will need the support of almost all of them if he’s to get his way.