Sen. Mitt Romney of Utah, the former Republican presidential candidate and former Massachusetts governor, is also, apparently, the man behind a Twitter account that uses the moniker “Pierre Delecto.”

Romney on Sunday admitted to McKay Coppins, a writer at The Atlantic, that he was responsible for the social media account, which he uses to covertly monitor political discourse and occasionally defend himself. It’s unclear what, if anything, Pierre Delecto is a reference to.

Several events preceded the admission.

First, The Atlantic published Sunday a profile of Romney, one of the few prominent Republican lawmakers to criticize President Donald Trump over his efforts to press Ukraine to investigate his Democratic rivals. Those efforts form the basis of an impeachment investigation by the House.

Trump lashed out in response this month, calling the senator on Twitter a “pompous ‘ass’ who has been fighting me from the beginning.” In one tweet, the president used the hashtag “#IMPEACHMITTROMNEY.”

In the Atlantic profile, Romney admitted to having what he called a “lurker account” — essentially a profile under a different name that he operated in secret to monitor the political conversation. But he declined to divulge the name associated with the account.

The admission spurred curiosity, particularly that of the online newsmagazine Slate.

Slate theorized that Pierre Delecto, or Twitter user @qaws9876, was Romney after it discovered the account among the Twitter followers of one of his grandchildren.

Slate noted that Pierre Delecto’s first follower was Romney’s oldest son, Tagg. The account was created in 2011, shortly after Romney announced his intention to run for president. The account also followed all of Romney’s children who are on Twitter and several former advisers, according to Slate.

The account also posted several telling replies to Romney-related tweets, which were captured by screenshot before the account was made private Sunday night.

In one tweet from May, Jennifer Rubin, a conservative blogger at The Washington Post, said Romney’s strategy on Trump was “non-confrontation verging on spinelessness.”

“Jennifer, you need to take a breath,” Pierre Delecto replied. “Maybe you can then acknowledge the people who agree with you in large measure even if not in every measure.”

The Slate article prompted many on social media to surmise that if Pierre Delecto was in fact Romney, he had concocted one of the most prolific social media pseudonyms for a public official ever (besting the former FBI director James B. Comey’s onetime moniker of Reinhold Niebuhr).

After Slate published its article, Coppins circled back with Romney to ask if he was indeed “Pierre Delecto.”

“Just spoke to @MittRomney on the phone, and asked him about Pierre Delecto,” Coppins said in a tweet. “His only response: “C’est moi.”’

A spokeswoman for Romney did not directly answer questions about the account Sunday night. But in an email, the spokeswoman sent a link to the tweet from Coppins describing Romney’s admission.

Neil Vigdor contributed reporting.