* Clinton's surging popularity raises questions on future plans
* Bill Clinton to carry family flag at Democratic convention
* Hillary Clinton to leave Obama administration in January
By Andrew Quinn
WASHINGTON, Aug 28 (Reuters) - As delegates gather next week for the Democratic National Convention, they will look in vain for one of the party's biggest stars.
Where in the world is Hillary Clinton?
The 2008 Democratic presidential candidate, frequently rated the most popular member of President Barack Obama's cabinet, will be half a world away from the North Carolina convention center when Democrats gather Sept. 4-6 to nominate Obama for a second term.
Clinton's head-spinning itinerary for that week, which will take her from the South Pacific to Asia to Russia's eastern port city of Vladivostok, is business as usual for the U.S. secretary of state, who has broken numerous travel records since taking the job in 2009.
Through it all, Clinton has studiously adhered to the rule that America's top diplomat must remain above the partisan fray. When asked touchy domestic political questions, Clinton's usual response is a wry, silent smile.
So it was no surprise when her staff confirmed she would skip the Democratic convention in Charlotte, the first she has missed since 1968.
Not that the event will be Clinton-free. Former President Bill Clinton will play a central role, giving the speech on Sept. 5 that will formally place Obama on top of the party's ticket, and the former president has already hit the airwaves in advertisements promoting Obama's candidacy.
The Clintons' daughter, Chelsea, is attending both the Republican and Democratic conventions, according to the William J. Clinton Foundation.
But Hillary Clinton -- if she can find the time -- will, like most Americans, watch the proceedings on TV.
"As secretary of state, she is no longer engaged in retail politics, but she remains a keen observer," said P.J. Crowley, a former Clinton White House staffer and State Department spokesman.
"I'm pretty sure she'll be closely monitoring what happens there. She has good sources, one in particular, who will be in a good position to tell her what happened."
"UNREAL AND UNSETTLING"
Hillary Clinton's aides, who dutifully describe her as fully focused on her international portfolio, declined to discuss her feelings about missing the convention.
Still, watching from the sidelines will be a change for Clinton, who attended her first convention -- a Republican one -- as a junior aide in 1968 and reported in her book "Living History" that she found the experience "unreal and unsettling."
After meeting Frank Sinatra and sharing an elevator with John Wayne at the Republican conclave in Miami, Clinton went as an observer to the 1968 Democratic convention in Chicago, dodging police charges against protesters and finding her own calling as an activist.
Clinton remained a fixture at Democratic conventions for the next four decades, dancing on stage in New York in 1992 after Bill Clinton was first nominated for president and becoming the first U.S. first lady to deliver a televised speech to delegates in Chicago in 1996.
Clinton went on to become a U.S. senator from New York and then a presidential candidate in her own right in 2008.
The largely nonpartisan Hillary of today is a far cry from the politician who questioned candidate Obama's national security credentials and, in the previous decade, deemed her husband's Republican critics part of "a vast right-wing conspiracy."
After the hard-fought 2008 primary campaign, she used the Democratic convention in Denver to rally the party behind her one-time rival.
"Barack Obama is my candidate. And he must be our president," Clinton said.
MISSING STAR POWER?
Clinton has remained Obama's loyal lieutenant, although she has also firmly maintained that she will step down from her current job at the end of his present term early next year to take a rest.
Rumors that she might want to swap jobs with Vice President Joe Biden -- or start planning a second run for the presidency in 2016 -- are routinely shrugged off with the same good-natured laugh.
Hank Sheinkopf, a veteran Democratic consultant based in New York, said Clinton's no-show at Charlotte could put to rest daydreams among some Clinton loyalists that she might yet be coaxed back into this year's electoral contest as a stand-in for Biden.
"Some will wish she were there, but it puts an end to any speculation that there might be a switch on the ticket," Sheinkopf said.
Other analysts say Bill is the right Clinton to step into the spotlight at this particular moment.
"She has made the right decision, which is not to in any way explicitly politicize herself at a time when we are facing multiple international crises," said Doug Schoen, a Democratic pollster who played an important role in Bill Clinton's 1996 re-election.
"And let's not forget: Bill Clinton is the most popular man in America right now. I think that says it all."
Still, few political observers believe Hillary Clinton's convention career is over for good. As one of the Democratic Party's most influential and best-networked mainstays, she will likely remain an important voice no matter which candidate wins this year's election.
"I would be surprised if she was not at the next Democratic convention, either as a former first lady, former secretary of state, or as a candidate herself," said Lee Miringoff, director of the Marist Institute for Public Opinion at Marist College in Poughkeepsie, New York.
"I bet she has already cleared her calendar."