Pete Souza/The White House/AP Photo

With  President Obama shifting  into campaign mode to raise money for his re-election effort, the White House has generally let reporters inside the events  at least long enough to record what he says to his top donors.

This week, though, Obama departed from that practice, meeting for more than an hour with big-dollar contributors - all behind closed doors.

The "campaign event," as the White House billed it, was at the  boutique Jefferson Hotel in Northwest Washington. A Democratic official said about 20 people attended and paid the maximum amount allowed: $35,800 for a ticket.

But anything  Obama told the group remains secret. The administration justified the decision to bar reporters by saying  Obama wasn't making a "formal" speech.

"Tonight the president is doing a meet-and-greet with a small group of people to benefit his campaign," read a statement from White House spokesman Josh Earnest. "Since the president is not planning to make formal remarks to the small group, this event will be closed press."

The situation invites a comparison to another  closed-press San Francisco fundraiser Obama headlined in 2008, when a supporter recorded him saying that people in small towns, faced with the loss of jobs, "cling to guns or religion." That comment cost him politically, and the campaign said that reporters would be allowed more access to such events.

On Wednesday, though, the Secret Service blocked off entrances to the Jefferson while Obama was entertaining his contributors. After Obama left the event, some of the donors lingered at the hotel bar. "We're not supposed to talk to you,"  said one male donor as he sipped wine. Another ran his finger over his lips as if zipping them shut and said, "No comment."

Nancy Conrad, a donor in a chattier mood, described the event as "a dialogue" with Obama. They talked about "what the president has done and going forward," she said. Obama spoke with every donor in the room individually, according to Conrad. This reporter was then told to leave by a person working for the campaign.

Reached the next day by phone, Conrad was more reserved. "This was really a closed meeting, and it was not open to the press," she said. "It was great. It was wonderful to talk with him. That's really all I can say."

Obama rarely speaks at campaign events without the press present. He did so last June at a hotel in Puerto Rico; in March 2011 at Washington's St. Regis Hotel; and a handful of times in the summer of 2010 before the midterms.

"At fundraisers where the president delivers remarks, there is at minimum a print pool reporter," campaign spokesman Ben LaBolt said in an email the day of the Puerto Rico event. "The president is not delivering remarks at this event."

"You have to wonder what was discussed at this one," said John Wonderlich, the policy director at the Sunlight Foundation, an advocacy group that fights for transparency, of Obama's Wednesday fundraiser at the Jefferson. "The question of whether it's formal or not seems ridiculous. Anything the president says is formal."

White House officials didn't respond to requests to clarify what they meant when they said  Obama wasn't making "formal" remarks at his closed fundraiser.

The White House says  often that it is the "most transparent administration in history," and to his credit, Obama has taken steps to be open, such as releasing the names of his top campaign donors. The Democratic National Committee has pressured Mitt Romney to do the same, and he has yet to do so.

The Republican candidates for president have had plenty of closed-press fundraisers, too. On Thursday, for example, Romney mingled privately at a Richmond, Va.,  hotel with supporters who paid up to $5,000 to see him.

On the general transparency front, Obama  has also put the names of visitors to the White House online, though an iWatch News investigation found that effort  to be flawed.

But Wonderlich said that some of Obama's former White House staffers were  now running a major political-action committee to benefit his campaign, despite the president's pledge not to accept money from so-called super PACs.

"The ultimate question is, is the president living up to his responsibilities as president for creating an accountable system?" Wonderlich said.

ABC News' Devin Dwyer contributed reporting.