Ben Roback is Head of Trade and International Policy at Cicero Group and a member of the US Embassy’s Young Leader’s UK programme.

Much has been written about the life and career of John Sidney McCain III since the news of his death was announced on August 25th.

An American prisoner of war, McCain went on to become a Congressman for Arizona’s first district and then Senator for his home state for 31 years. In many ways, he was one of the standout senators of an entire political generation.

History will reflect on his ultimately unsuccessful presidential campaign in 2008, but McCain’s legacy will be far from defined by it.

In the current era of tribal partisanship, McCain was an old-fashioned pillar of ‘regular order’ in the Senate, typified by an August 2017 op-ed in the Washington Post. In a town beset by political gridlock that makes Congress incapable of performing its basic functions such as passing bills, McCain called for committees of jurisdiction to have time to do their job and for Congressional leadership to devote time on the Senate floor to debate and amend proposals.

He was, in many ways, a lone voice calling for a return to a more civil political era. Impassioned speeches on the Senate floor become the norm; few of his colleagues heeded his advice.

Standing up to President Trump

Senator McCain and Donald Trump clashed more than once. On the campaign trail, Trump said he didn’t think McCain was a war hero because he had been captured in Vietnam as a naval aviator. Ever the man of class, McCain did not cite the fact that Trump avoided conscription through a series of student deferments and a medical exemption.

In the Senate, McCain frustrated the President more than any thinly veiled insult ever could have done. Overhauling the Affordable Care Act was a unifying issue across the Republican Party during Barack Obama’s tenure, and so become the top legislative priority for Trump when he assumed office. After months of the ‘repeal and replace’ campaign in Washington, the decisive vote came down to McCain.

Standing dramatically in front of the Senate chair, he turned his thumb down like a Roman emperor, condemning ‘Skinny Repeal’ to failure. The standout piece of legislation by a Republican president, rushed through a Republican-majority House and Senate was not expected to be killed by a Republican Senator. Afterwards, McCain said:

“I’ve stated time and time again that one of the major failures of Obamacare was that it was rammed through Congress by Democrats on a strict party-line basis without a single Republican vote. We must now return to the correct way of legislating and send the bill back to committee, hold hearings, receive input from both sides of the aisle, heed the recommendations of nation’s governors, and produce a bill that finally delivers affordable health care for the American people. We must do the hard work our citizens expect of us and deserve.”

In many ways, that one moment typified McCain as a free thinker. It is not so much that he was unbound by the shackles of party politics, but more that Washington has become significantly more partisan around him. In that role, he will need replacing – they are vast shoes to fill.

A check on a President hell-bent on stretching executive power

It is no secret that the President has continually sought to expand the power of the Executive Office, while seeking to ignore the restraints of the judicial system and rule of law. That made the likes of Senator McCain even more important. It is far from obvious who will replace him in that mould.

His immediate replacement will be decided by Arizona Governor Doug Ducey, a Republican, who is legally required to fill vacancies in Arizona’s US Senate delegation. He will appoint McCain’s replacement, who by law must be from the same party as McCain. The new Republican Senator will stay in office until first facing re-election in 2020. The Arizona Republic, a local news outlet, names a shortlist headed by Cindy McCain, a clear choice to fill her husband’s seat.

In Congress, the question in sharp focus is less about who will fill the vacated Senate seat for the next two years and more about who will take up McCain’s mantle as an outspoken voice from within the Republican Party. In short, there is no obvious successor.

Senator Jeff Flake, Arizona’s other representative in the Senate, had been the next closest thing to McCain in his willingness to buck party politics and speak out against the administration. Flake himself is retiring and will not seek re-election in November, meaning the leadership will no longer be concerned with the second Republican rebel in the Senate. Additionally, Senator Bob Corker of Tennessee is also retiring.

Senate Leader Mitch McConnell might breathe a quiet sigh of relief – McCain, Flake and Corker were the fifth, sixth and seventh least supportive Republicans of the leadership’s legislative agenda in Congress (according to the FiveThirtyEight tracker).

Few Republicans on Capitol Hill could consider themselves worthy successors of McCain’s legacy of independent thinking and attitude of defiance. Senators Susan Collins, Mike Lee, and Lisa Murkowski are less reliable Republicans than McCain became, but that is priced in given the delicate balance between Republicans and Democrats in the purple states they represent.

In Senator Rand Paul, the upper chamber has the closest thing possible to a libertarian who thinks and acts outside the control of the Republican leadership. Though a theoretical successor to McCain’s independence, the Kentucky Senator has forged a far closer relationship with the President in recent months as the two routinely bond on the golf course. In a similar fashion, Senator Lindsey Graham had previously fought with Trump but has since mellowed, saying in April he would support Trump’s 2020 re-election bid.

In the latest YouGov poll, 84 per cent of registered Republicans approve of the job the president is doing. Owing to the near-total loyalty the Republican base is consistently showing towards Trump, there is little to no incentive for Republicans in the House or Senate to break with the administration on big ticket issues like healthcare, trade, or the Mueller investigation. As recent primaries have shown, not least in Florida last night, state-wide structures of the GOP are becoming increasingly dominated by Trump supporters.

Replacing the irreplaceable

In the age of fake news, sub-tweets and gaslighting, John McCain stood out as a pillar of a bygone political era. Despite what you might have thought of his political views or campaign for the presidency, he was what we would like our politicians to be – on both sides of the Atlantic.

A statesman with a sense of humour, John McCain cannot be replaced. Eulogies to be read at his funeral by former presidents Barack Obama and George Bush will be lasting proof of a that rare ability to cross the political divide and bring people together.