The posters went up last week, 14 in Union Station. On each of the large displays, a thought bubble rises up from a picture of a beautiful 8-year-old: “President Obama’s daughters get healthy school lunches. Why don’t I?”

A Washington nonprofit that advocates nutrition-policy reform paid $20,000 to get its message across and carefully maneuvered Metro’s tangle of regulations to display its posters. Metro gave it a go — but the White House did not, according to the group. Within 24 hours of the signs’ appearance, the White House asked the Physicians Committee for Responsible Medicine to take down the ads, which feature Jasmine Messiah, a vegetarian who attends a Miami-Dade County public school that, she says, offers no vegetarian or vegan lunch options.

The Physicians Committee has declined to take down the posters.

PCRM President Neal Barnard, a nutrition researcher, says he received a phone call regarding the posters Aug. 4 (a day after they went up) from Associate Counsel Karen Dunn and Deputy Associate Counsel Ian Bassin.

“They’re very nice people. I like them a lot,” Barnard says. “But they called and said: Please take those down, you can’t mention the kids and so forth. . . . They felt that mentioning the president’s children was off-limits. They said [they’re] not going to allow the use of their daughters as leverage.”

The fact that the poster mentions the president’s children has been the main point of contention, though neither the children’s names nor their images appear. That reaction doesn’t come as a complete surprise; when Ty Inc. marketed dolls in January named Sweet Sasha and Marvelous Malia, the first lady made her objections clear, and the toy company stopped using the girls’ names. The First Lady’s Office declined to comment for this story.

To Frank Luntz, a Republican political consultant, the White House’s response to the posters is hardly shocking.

“The children of the president are always off-limits. Always. No exceptions,” Luntz says. “No ifs, ands or buts. And while it may draw short-term attention to the issue, the White House will hate the organization for it. And I assure you they will be punished. You don’t mess with the president’s children. It’s an unwritten rule.”

Luntz says that the added publicity from the White House’s response will not benefit PCRM’s agenda. “What matters is not whether people are aware of your campaign,” he says. “What matters is your success. And if the White House hates you, then it’s not successful.”

“I do not think you can use the president’s daughters for some cause — good or otherwise — that they don’t play a role in,” says Bonnie Angelo, a former White House correspondent for Time magazine and author of “First Families: The Impact of the White House on Their Lives.”

“It’s very hard for the presidential family to keep their daughters balanced in terms of getting too much exposure, and I think the Obamas have done a remarkable job of achieving that balance,” Angelo says. “I think this goes beyond what’s allowable.”

Barnard is still in communication with the Office of the White House Counsel, which asked Barnard to remain “open” to further discussion. He says he is.

Initially, “what they said was that they wanted me to remove [the posters] voluntarily, but made it clear that they viewed this as something that could lead to legal action if I wasn’t responsive. But that was an implication. If this story comes out as Obama versus Us, I don’t want that story,” says Barnard, whose organization contacted The Washington Post on Monday about the dispute.

The posters, several of which appear in a corridor leading from Amtrak gates to the Metro platforms, are large, wall-mounted displays, strategically placed to catch the eye of Hill commuters.

“The main reason we put the posters there, of course, is for congressional staffers who get off at Union Station and they have to walk down that corridor,” says PCRM’s media relations manager, Jeanne McVey.

Barnard says that the reception he’s received regarding the poster has been positive and that he plans to leave the posters up until Aug. 31, the full period they were scheduled to be in the Metro stop.

“It’s a beautiful ad,” Barnard says. “We’ve been on Capitol Hill for a long time, working with members of Congress, and it’s fair to say there’s a lot of support on Capitol Hill for exactly what we’re doing.”

PCRM is advocating vegan and vegetarian lunch options at public schools nationwide. Barnard hopes that when Congress weighs in on the Child Nutrition Act, which comes up for reauthorization in October, the presence of these options will be made mandatory. He cites Rep. George Miller (D-Calif.), chair of the House Education and Labor Committee, as a key supporter. And Barnard says he hasn’t heard of any opposition to the posters apart from that voiced by the White House lawyers who contacted him.

Barnard says he doesn’t see anything compromising or controversial about the poster, which features Jasmine Messiah standing impishly, arms crossed, in a red dress against a red background, with a clip-art-style thought bubble aligned with her left pigtail. For Barnard, juxtaposing Jasmine with Sasha and Malia was particularly important.

“The direct comparison is: You have affluent children with access to healthy foods, and disadvantaged children have the same rights to the same kinds of healthy meals as affluent kids. And we are fighting for that fairness, so we felt that making that statement as directly as we could was important.”