Outside, Delta supporters crowded a winding staircase, hoping for a seat inside the second-floor room. Their line stretched to the basement and down a corridor.
US Airways appeared to have no supporters present beyond executives.
"If the US Airways people think this is such a great deal, why aren't they here?" asked Cathy Cone, chairwoman of the Delta Retirement Committee.
From the start, the hearing seemed tilted in Delta's favor. It kicked off with Sen. Johnny Isakson (R-Ga.) introducing Grinstein, saying the chief executive has done "great things" for Delta.
Mark Cooper, research director of Consumer Federation of America, testified that because Delta and US Airways have so many overlapping routes, a merger inevitably would reduce competition. "I think consumers would be hurt," he concluded.
Robert Roach, a vice president of the International Association of Machinists and Aerospace Workers, noted that when American Airlines purchased TWA in 2001, it promised to maintain a hub in St. Louis. "That once-bustling hub with over 300 flights per day has now been reduced to less than 100," he said.
Grinstein predicted 10,000 jobs would have to be cut for US Airways to make the merger work.
To believe neither jobs nor service would get cut in the merger, he said you also "have to believe in Tinker Bell."
Parker said a merger would not cause layoffs, though many jobs would not be refilled as people left the company. His plan is for the merged carrier to carry Delta's name, but that the headquarters location hasn't been settled.
Andrew Steinberg, a Transportation Department assistant secretary, seemed to offer Parker the only hint of support.
He refused to comment on the proposed Delta deal, but said that in general, consolidation does not necessarily harm consumers.
"We must allow failing firms to exit the business if market forces decide that assets should be reallocated to more efficient firms," he said.
Staff writer Russell Grantham contributed to this article.
Parker said his improved bid for Delta has generated little response from the Delta creditors and that time is running out on the offer.
The creditors' decision came after an efficient campaign by Delta to torpedo the offer both publicly and behind the scenes.
Delta and its creditors may see a post-bankruptcy link-up with Northwest as a better alternative to the US Airways bid.
The merger plot just thickened at Delta Air Lines. US Airways bumped up its takeover bid for the Atlanta-based airline by 20 percent Wednesday, to $10.3 billion, adding a Feb. 1 deadline in...