On Tuesday, Delta Air Lines formally rejected US Airways' $8.4 billion merger offer and filed a reorganization plan centered on the carrier emerging from Chapter 11 by next spring, the AP reported. Creditors must now vote on whether or not to approve the reorganization plan and the court must further approve the plan. Delta's board unanimously rejected US Airways' takeover offer, the AP noted, with Gerald Grinstein, Delta's CEO, adding during an analyst conference call, "US Airways is the worst of all potential merger partners."