Parker, who was the head of America West when it merged with US Airways in 2005, has been trying to merge with another airline for years. He's failed to court partners such as Delta.
"It has been firmly established that US Airways is for sale," Horton said.
But he pointed out that Parker's last merger didn't go very smoothly. US Airways has had a difficult time merging the seniority lists of its two pilot unions.
Friedenzohn, of Embry-Riddle Aeronautical University, said any American-US Airways union wouldn't be easy.
"US Airways is in some ways still operating as two separate carriers," he says. "Adding a third pilots unions to the mix would add some complications."
But somehow Parker has managed to score with American's unions. The labor leaders joined him at the head table at his National Press Club appearance.
Horton acknowledged "it's a difficult process" and that American's unions for pilots, flight attendants and mechanics support a merger with US Airways. But he said American's tentative contracts are firmer for workers than the promise of a merger.
"He made a deal to make a deal," Horton said. "What we made are actual tentative agreements, with all the language written down."
Horton also dismissed suggestions that it's in his financial interest to drag his feet on a merger with US Airways because he could receive as much as $60 million if American emerges from bankruptcy independently.
"My focus is 100% on what creates the most value for our owners. That's my job," Horton said. "It's not about me … I don't think for a minute about such things."
Although he complains that American is foot-dragging on his merger bid, Parker doesn't accuse Horton of doing it out of personal financial motives.
However, Parker said at the press club, "I find it noteworthy that the only opposition that seems to exist to this merger is the senior management at American."
"I don't want to guess as to why it is that they don't support it," Parker said. "But we are hopeful that we will find that we can get their support at some point in the future."