WASHINGTON — In a move that surprised his most loyal supporters and former staff, Mitt Romney told several donors Friday that he’s seriously considering a third run for the White House — a dramatic shift for the former Republican presidential nominee after months of insisting his career in politics is over.

Romney attended a private gathering of donors at the New York offices of Woody Johnson, a leading Romney donor in 2012 and owner of the New York Jets, several people with direct knowledge of the meeting told The Associated Press.

All spoke under condition of anonymity, as they were not authorized to speak publicly about the private discussions. The meeting was first reported by The Wall Street Journal.

The news from Romney comes as former Florida Gov. Jeb Bush marches swiftly toward a 2016 bid of his own, which threatens to win much of the support from the Republican establishment that fueled Romney’s last campaign. Bush has spent recent weeks hosting private fundraising meetings across the country and is courting top talent to staff a potential campaign.

While the first primary contests in the 2016 race are roughly a year away, and no one has formally declared his or her candidacy, more than a dozen high-profile candidates are considering getting into the race.

One person at Friday’s meeting, which included a conference call and was attended by roughly 15 of Romney’s most generous and loyal past donors, said the gathering was meant to be an open-ended discussion among old friends. Several donors in the room had already privately committed to other 2016 contenders but wanted to hear from their one-time favorite.

Some were caught by surprise when Romney suggested he was considering a 2016 campaign after months of public denials. Others asked Romney what he would do differently after a 2012 campaign in which he struggled at times to connect with middle-class voters.

Toward the end of the hourlong session, Romney told his one-time allies they should tell their friends that a Romney 2016 campaign is under serious consideration, according to one person in the room.

Romney also acknowledged he needs to act quickly should he decide to run, said a top GOP donor briefed on the meeting.

Were Romney moving to join the 2016 field, many who served in senior roles in his previous campaigns assumed they would have been given a heads-up about an announcement.

In addition to Johnson, Friday’s meeting with Romney included Emil Henry Jr., an assistant treasury secretary in Bush administration; Alexander Navab, of the financial firm KKR; Patrick Durkin, a managing director at Barclays; Clifford Sobel, managing partner of Valor Capital Group; and Edward C. Forst, CEO at Cushman & Wakefield.

Romney, who ran unsuccessfully for president in 2008 and 2012, has repeatedly insisted he would not run again. At a political rally in New Hampshire last summer, he said he would “get behind the one who I think has the best chance of winning.”

“We’ll get someone who can win,” he added.