Perhaps most significant of all could be the role Romney plays in the Senate once Special Counsel Robert Mueller issues his report on possible collusion between Russian and the 2016 Trump campaign, not to mention the many other ongoing investigations of financial improprieties in the Trump organization. The Democratic majority in the House will be much more likely to impeach the president if it has reason to believe there’s a chance that 20 or so Republican senators might be persuaded to join the Democratic minority in the Senate in voting for conviction and removal from office. Having an outspoken and widely respected critic of the president in the chamber can only make that more likely. It will also give Romney enormous leverage in negotiating with the White House on other issues.

All told, Romney’s op-ed is a big deal. It’s a sign that the civil war in the GOP that so many pundits talked about during the 2016 election cycle isn’t over yet. The battle for the soul of the party goes on. And Mitt Romney has now placed himself firmly on the front lines of the side arrayed against Donald Trump.