“If I could get a really outstanding person to run for my position, I might very well consider [retiring],” he told National Journal in April, adding, “Mitt Romney would be perfect.”

Hatch hand-delivered a memo to Romney last year laying out the reasons he should run for his seat, according to a source with knowledge of the document. And as I first reported at The Atlantic last spring, Romney was seriously exploring a bid. People close to him told me at the time that he was alarmed by President Trump’s incompetence and worried about the threat his presidency posed to the long-term health of the Republican Party. Still, he’d made clear that he would not run for the seat unless Hatch decided to retire.

By last October, people close to Hatch were telling me that the senator had made clear in private that he planned to retire. But with the prospect of a Senator Romney growing more likely, the Trump White House made a last-ditch attempt to keep Hatch around for another term—complete with a presidential visit to Utah, and enthusiastic lobbying behind closed doors.

Trump’s efforts were not lost on the senator, and as Utah’s political class waited last month for him to announce his decision, several sources told me they were worried Hatch was having second thoughts.

In the end, though, Hatch followed through on his plans to bow out, opening the door for a Romney bid. As the first Mormon to win a major-party presidential nomination, Romney is immensely popular in Utah, and is widely expected to win easily if he runs. As an elder-statesman figure in the GOP, he has distinguished himself as one of the most outspoken Republican critics of Trump.

During the 2016 primaries, Romney gave a scathing speech attacking Trump as “a phony” and “a fraud,” and refused to endorse him even after he won the nomination. When Trump was elected, Romney had dinner with him to discuss a potential cabinet pick—but in the year since, he has continued to criticize the president. Last summer, he wrote that Trump’s handling of Charlottesville had “caused racists to rejoice, minorities to weep, and the vast heart of America to mourn.” And after Trump endorsed Roy Moore for the Senate in December, Romney tweeted that his election “would be a stain on the GOP and on the nation.”

Romney replacing Hatch in the Senate could be a nightmare scenario for Trump—a staunch ally making way for a high-profile, newly empowered adversary. It remains to be seen, however, how Romney would view his project as a senator. Would he see himself as an anti-Trump truth-teller defending conservative principles from the poison of Trumpism? Or would he try to use his influence to pass major Republican legislation? People close to Romney tell me both scenarios are plausible. First, though, he’ll have to decide if he’s running.

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