By Fabienne Faur

WASHINGTON — Valerie Trierweiler pushed the frontiers of US diplomatic protocol on Friday as she took her first steps as France's new -- and unmarried -- first lady ahead of the G8 and NATO summits.

The domestic partner of Francois Hollande -- they've been a couple since 2007 -- skipped a lunch Friday between the newly elected French president and Secretary of State Hillary Clinton.

But she was eagerly awaited at a French embassy reception later in the day to be attended by 2,000 French expatriates, and at a White House lunch on Saturday for G8 spouses hosted by US First Lady Michelle Obama.

Then on Sunday, in Chicago, venue of a NATO summit, she'll join Mrs Obama and fellow NATO spouses on a visit to the south-side Gary Comer Youth Center followed by a private dinner at the Art Institute of Chicago.

For Monday, Trierweiler is scheduled to visit a French international school in Chicago.

"There is no established rule for how questions like these are addressed," Caitlin Hayden, a White House spokeswoman, told AFP when asked about the protocol surrounding the unmarried partner of a head of state.

"Ms Trierweiler has been invited to participate in all spousal programs at both the G8 and Chicago," Hayden said. "We look forward to welcoming her to the United States."

For the US media, the 47-year-old journalist -- twice divorced and the mother of three children -- is seen as smart, talented, chic and elegant, bearing some resemblance to film legends Lauren Bacall and Katharine Hepburn.

But they've been puzzled about how to describe the female half of the first unmarried occupants of the Elysees Palace, with CNN favoring "girlfriend" and others opting for "spouse," "partner" or "companion."

William Galston, a political analyst at the Brookings Institution think tank in Washington, told AFP he thought most Americans would accept the Hollande-Trierweiler relationship as something typically French.

Many Americans remember the children born to France's last Socialist president Francois Mitterand in and out of wedlock, as well as Hollande's twice-divorced predecessor Nicolas Sarkozy, he said.

And they can equally remember Sarkozy's glamorous model-turned-songstress wife Carla Bruni, whose list of ex-lovers included rock stars Eric Clapton and Mick Jagger.

While Americans can accept a divorcee in the White House, said Galston, citing the example of Ronald Reagan, it will be some time yet before they consent to an unmarried but otherwise attached president.

Photo AFP, Yuri Gripas