But his decision not to run next year does appear to have been made quite recently. Chaffetz had given no public indication that he was planning to abandon his seat next year. In fact, when I interviewed him last month for a profile, I asked him how much longer he planned to stay in the House, and he replied, “Not too much longer. You can be the chairman up to six years.” He has only served as oversight chairman since 2015.

Nor did Chaffetz make his plans known privately among allies in his home state. According to Utah GOP sources, even high-level elected officials close to the congressman didn’t learn of his decision until late Tuesday night.

“He kept this very much under wraps,” one senior Republican told me. “The political class here is reeling right now. Nobody has any idea what’s going on.”

Immediately following Chaffetz’s announcement, observers speculated that he was stepping aside to prepare for a gubernatorial bid in 2020—a race he told me last month he would “definitely maybe” enter. But the Republican insiders I spoke to Wednesday were skeptical that future career ambitions would lead him to forsake a high-profile platform like the one he has now.

A spokesperson for Chaffetz did not immediately respond to a request for comment. But in an interview with Utah’s KSL talk radio Wednesday, he said his decision was motivated primarily by a desire to spend more time with his family.

Meanwhile, as speculation swirls in Utah political circles about Chaffetz’s motivations, the announcement has set off a scramble in his home state to determine who will replace him.

According to one senior GOP source, it is not yet clear whether Chaffetz will finish his term, or ultimately decide to resign early. Democrat Kathryn Allen, a darling of the national progressive media, has built up a substantial war chest, though she still faces an uphill climb in an incredibly conservative district. And a person close to Evan McMullin— a conservative Mormon and former independent presidential candidates—tells me he is considering a bid for the seat. Other local Republicans will no doubt enter the fray.

Even before Chaffetz announced his abrupt exit, his political luck had suffered a steep decline when Trump was elected. As oversight chairman, he was preparing to spend four years investigating President Hillary Clinton’s alleged scandals and misdeeds. Then the Republicans unexpectedly seized control of the White House, leaving Chaffetz with the unenviable task of policing his own party. It was a fraught job to begin with, and his casual attitude toward the Trump family’s potential conflicts of interest—demonstrated in his interview with me last month—has only increased the pressure on him.

“Aside from Trump and Clinton,” one Utah Republican told me last month, “nobody’s fortunes changed more on presidential election night than Jason Chaffetz.”

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.