Flying to St. Louis late Saturday night, Sen. Hillary Rodham Clinton's campaign press secretary came back to the reporters aboard the plane and asked if they would like a visit from Chelsea Clinton.
The hitch was that the conversation would be off the record, meaning that nothing the former first daughter might say could appear in print. Chelsea Clinton, 27, has emerged as an important part of her mother's campaign entourage. But she seldom gives interviews and remains something of an enigma to the press pack traveling with the Clinton campaign.
Some of the journalists on the flight agreed to the condition; others did not. Told of the split, Chelsea Clinton stayed away. The Clinton press secretary, Jay Carson, was exasperated.
In the run-up to the crucial nominating contests of Super Tuesday, the terms of engagement between the press and the two main Democratic presidential candidates are a growing source of friction.
Earlier, reporters traveling with Clinton had agreed that if the candidate came to the back of the plane to talk with them, those comments would be considered off the record. But by Saturday, many told campaign aides that the arrangement left them uncomfortable. They wanted the freedom to report whatever Clinton said, especially if it was at variance with any of her public statements.
So journalists from outlets including the Los Angeles Times, Associated Press, New York Times, Chicago Tribune and National Public Radio said that if Clinton wanted to speak to the press aboard the plane, it would have to be for publication.
On Sen. Barack Obama's 737, a similar dust-up played out Saturday.
Obama had been largely standoffish with the press corps that follows him, rarely venturing to the back of the campaign plane to talk.
But since his win in South Carolina, Obama has sauntered back to the press section more often, creating a need for ground rules.
On Saturday, he walked back from the first-class cabin and said his presence was off the record. He proceeded to talk about topics from the Super Bowl (he's rooting for the New England Patriots) to the state of the race (making progress).
But reporters from the larger print outlets objected. A handful turned on tape recorders, and the Illinois senator quickly left.
A fervent discussion about ground rules ensued between the press corps and the campaign staff, with one press aide telling reporters to check with their colleagues on the Clinton plane about ground rules there.
"She's our competitor now," the aide said. "It can't be a double standard."
As the Obama plane took off from Delaware and headed for Chicago on Sunday afternoon, the matter was still unresolved.
In the Republican contest, the issue has not had the same urgency. Sen. John McCain (R-Ariz.) is famous for giving the press generous access.
Reporters and television network crews take turns rotating on and off his bus, dubbed the "Straight Talk Express." McCain rarely goes off the record. He generally asks reporters if he can speak privately only when the subject is his family.
Former Massachusetts Gov. Mitt Romney rarely talks to the press on his plane, but when he does there are no restrictions.
As for Clinton, another showdown of sorts took place Sunday. The New York senator's campaign invited reporters to watch the Super Bowl with her at a restaurant in Minneapolis -- provided the event be off the record.
After some reporters objected, the campaign huddled. Aides came back with a counter-proposal: The watch party would be on the record -- but Carson asked reporters to show restraint and be "normal human beings."
Times staff writers Maeve Reston and Seema Mehta contributed to this report.