Government watchdog groups are criticizing the White House's decision to withhold the names and identities of 18 people who stood behind President Obama on Tuesday as he kicked off a new publicity campaign to promote Obamacare.

Nineteen people joined the president on stage at the Executive Office Building event earlier this week. During his remarks, Obama identified only one of them, Monica Weeks, who introduced the president after telling her story of how she developed Crohn's Disease at age 19 and benefited from the Affordable Care Act because it provided coverage for expensive treatments and allowed her to remain on her parents' plan into her mid-20s.

In taking the stage, Obama thanked Monica and “everyone standing behind me.” Later in his speech, he called on Republicans critical of the new health care law to check with “the people who are here today and the people they represent all across the country whose lives have been changed for the better by the Affordable Care Act.”

But Obama never said who those people were, and the White House has declined to identify them, as the Washington Examiner's Byron York first reported Tuesday.

Asked about the participants at the event, White House spokeswoman Jessica Santillo said only that the people joining Obama on stage were “consumers who are benefiting from the Affordable Care Act, grassroots supporters of the law and representatives from supportive businesses.”

The White House gave the same vague statement to the reporter covering the event for the press pool that day.

Advocates for greater government transparency said they find the secrecy surrounding the names and stories of the individuals standing behind the president Tuesday odd, especially considering Obama's pledge to run the most transparent administration in his history.

“[It] seems totally bizarre,” said Melanie Sloan, the executive director of Citizens for Responsibility and Ethics in Washington. “Posing behind the president at a press event isn't a good way to preserve anonymity.”

Sloan, who joined a legal fight to try to force the Obama administration to provide greater details of those visiting the White House, said she finds the secrecy surrounding the people on stage Tuesday particularly odd because “eventually someone will figure out who they are by combing through the White House visitors logs.”

Obama, as part of his pledge to offer unprecedented government transparency, is the first president to provide online information about White House visitors. The White House periodically releases batches of visitors' names and posts them online.

But transparency advocates complain that the information is still far from ideal – the logs are usually several months old and lack identifying details beyond a visitor's name. They also often include typos and names of people cleared to enter the building who never actually visited. The latest release of the logs dates back to August 2013.

The botched rollout of and Obama’s broken promise that consumers could keep their health plans despite new Obamacare rules have seen the president’s approval rating hit new lows in numerous polls. Americans are also giving Obama record-low marks on his trustworthiness and ability to manage the government.

Bill Allison, the editorial director of the Sunlight Foundation and a veteran investigative journalist, said the problem with the president's Tuesday event wasn't limited to the secrecy surrounding the people who stood behind the president.

To regain the American people's trust, Allison said, the president needs to hold more press conferences in which he takes questions from reporters.

“The president needs to level with the American people about what went wrong with the website, who's to blame and how he'll fix it,” Allison said. “And he needs to do it at a press conference where he can be questioned.”

“Having a staged event with cheering, mostly anonymous beneficiaries of the act, is not going to restore anyone's confidence in the administration,” he added. “The fact that they won't release the names suggests, that once again, the White House is hiding something.”

The secrecy surrounding Tuesday is inviting comparisons to an Oct. 21 event that was intended to reassure the public about the Obamacare rollout, but instead turned into an embarrassment for the White House.

The October event — held at the height of the troubles — was supposed to showcase people who had successfully navigated the system, but further scrutiny of the biographies the White House released of those who gathered with Obama on stage showed many had not completed their online enrollments. In some cases, those who appeared with Obama had not even begun the online process.

Obama's remarks during Tuesday's event, calling on Republicans to contact the people who attended to hear their stories, gave GOP leaders an opening as well to slam the administration’s Obamacare campaign.

“For the self-proclaimed 'most transparent administration in history' this should be a no-brainer,” said Brendan Buck, a spokesman for Speaker John Boehner, R-Ohio. “If these people are going to be used as political props by the White House to represent the success of Obamacare, the media ought to be able to confirm the stories.”

“Otherwise, given the dubious claims of the past, it's just more evidence this White House has no credibility,” he added.