After criticizing then-candidate Trump during a scripted TV appearance back in 2016, Mitt Romney largely kept quiet as he ran for - and won - his senate seat in Utah (with the help of the president's endorsement). But now, just two days before his swearing-in, Romney is seeking to burnish his reputation as the leader of the Republican "#Resistance" to the president.

In a Washington Post op-ed published in Wednesday's paper, Romney revived many of his favorite criticisms of the president, citing his failure to "do the right thing" and "inspire and unite" the American people. Romney had hoped Trump would dispense with the taunting and name-calling embraced by Trump during the campaign once he had won the election, yet "he did not." And while some of Trump's early staffing picks proved encouraging, Romney accused the president of the cardinal sin of American politics: Being profoundly and aggressively unpresidential. Or as Romney puts it, the president's "Character falls short."

It is well known that Donald Trump was not my choice for the Republican presidential nomination. After he became the nominee, I hoped his campaign would refrain from resentment and name-calling. It did not. When he won the election, I hoped he would rise to the occasion. His early appointments of Rex Tillerson, Jeff Sessions, Nikki Haley, Gary Cohn, H.R. McMaster, Kelly and Mattis were encouraging. But, on balance, his conduct over the past two years, particularly his actions this month, is evidence that the president has not risen to the mantle of the office.

Yet, interestingly enough, it's not Trump's policies to which Romney objects - on the contrary, Romney's list of favorable Trump policies includes almost the entire Trump agenda.

It is not that all of the president’s policies have been misguided. He was right to align U.S. corporate taxes with those of global competitors, to strip out excessive regulations, to crack down on China’s unfair trade practices, to reform criminal justice and to appoint conservative judges. These are policies mainstream Republicans have promoted for years. But policies and appointments are only a part of a presidency.

Though there is one aspect of the Trump agenda with which Romney disagrees: Trump's decision to withdraw troops from Syria and Afghanistan, decisions that Romney believes have put global security at risk and shaken the confidence of the US's Democratic allies.

The world is also watching. America has long been looked to for leadership. Our economic and military strength was part of that, of course, but our enduring commitment to principled conduct in foreign relations, and to the rights of all people to freedom and equal justice, was even more esteemed. Trump’s words and actions have caused dismay around the world. In a 2016 Pew Research Center poll, 84 percent of people in Germany, Britain, France, Canada and Sweden believed the American president would “do the right thing in world affairs.” One year later, that number had fallen to 16 percent.

And following the departures of Mattis and Kelly, the Trump administration "made a deep descent" in December.

The Trump presidency made a deep descent in December. The departures of Defense Secretary Jim Mattis and White House Chief of Staff John F. Kelly, the appointment of senior persons of lesser experience, the abandonment of allies who fight beside us, and the president’s thoughtless claim that America has long been a “sucker” in world affairs all defined his presidency down.

But in Romney's view, it's not Trump's actions that matter. It's his words.

To a great degree, a presidency shapes the public character of the nation. A president should unite us and inspire us to follow “our better angels.” A president should demonstrate the essential qualities of honesty and integrity, and elevate the national discourse with comity and mutual respect. As a nation, we have been blessed with presidents who have called on the greatness of the American spirit. With the nation so divided, resentful and angry, presidential leadership in qualities of character is indispensable. And it is in this province where the incumbent’s shortfall has been most glaring.

While Romney professes his commitment to his political ideals, and insists that he would pursue them without consideration for partisan divides, his op-ed appears to be less a substantive political declaration and more an example of Trump-tweet baiting at its finest. To that end, Trump took to twitter Wednesday morning to bash Romney in a tweet, questioning whether Romney was setting himself to be "a new Flake" and exhorting the former governor to focus on areas where "he can be helpful" like border security. But the president couldn't resist a jab about Romney's unsuccessful presidential bid, adding "I won big and he didn't."

Here we go with Mitt Romney, but so fast! Question will be, is he a Flake? I hope not. Would much prefer that Mitt focus on Border Security and so many other things where he can be helpful. I won big, and he didn’t. He should be happy for all Republicans. Be a TEAM player & WIN! — Donald J. Trump (@realDonaldTrump) January 2, 2019

But more importantly, as the first Democrats launch their primary campaigns for 2020, is Romney laying the foundation for a primary bid of his own?