Merkel invited Bruni-Sarkozy to Berlin in her role as a global ambassador for anti-AIDS efforts during a meeting with her and French President Nicolas Sarkozy on the sidelines on a UN poverty summit in New York this week.
Despite reticence by some deputies, the chancellor's spokesman Steffen Seibert late Thursday said Merkel backed Bruni-Sarkozy in her bid to address the budget committee of the Bundestag lower house.
"The chancellor thinks it is a good idea so Ms Bruni-Sarkozy can present important arguments" on behalf of the Global Fund to Fight AIDS, Tuberculosis, and Malaria, Seibert said. But he added that the final decision remained with the budget committee.
Germany has said it plans to cut its contribution to the Global Fund while France has pledged to hike its share by 20 percent over three years and called for other countries to follow suit.
German deputies, however, were cool to the idea of a visit by Bruni-Sarkozy.
"We have not received any request," the head of the budget committee, Petra Merkel of the opposition Social Democrats, told news agency AFP.
"If I received one, I would examine whether it was serious or not" and then advise the committee, she said.
"We had a similar case with the (U2) singer Bono, who wanted to speak to the committee a few years ago but we refused because it did not comply with our rules," she said, referring to a decision made in 2008.
Another member of the committee, Norbert Barthle of Merkel's Christian Democrats, said an audience with Bruni-Sarkozy would be "highly unusual."
"It would violate our rules," he told AFP. "On the committee, in principle we do not invite representatives of special interests. If we open the door to that, we would have to receive every representative of a social welfare and economic association or lobbyists."