"We're raising the offer to eliminate any doubt which proposal is better," US Airways CEO Doug Parker told "Squawk Box"
Parker admitted it is very tough to put a valuation on Delta currently. But while there is no roadmap for taking over a company in bankruptcy, the raised offer should make the decision much easier for the creditors, he said.
Based on Delta's own methodology in valuing the company the offer is worth between $12.7 billion and $15.4 billion, US Airways said.
"We just want to make sure everyone is looking at it on an apples-to-apples basis," Parker said.
Delta spokeswoman Betsy Talton told the Associated Press the airline had no immediate comment.
US Airways said the increased offer is set to expire on Feb. 1 unless creditors indicate support for the start of the due diligence process, which would open up Delta's books to US Airways. US Airways also wants Delta to postpone a Feb. 7 bankruptcy hearing involving its reorganization plan.
But Parker stressed that it was not asking creditors to sign off completely on the deal before the end of the month.
"This is not asking them to pick one or the other, just to let us keep going forward," he said on "Squawk Box."
Executives of Atlanta-based Delta have said they oppose a buyout by US Airways. The nation's third-largest carrier has filed a reorganization plan that calls for it to emerge from bankruptcy by the middle of this year as a standalone company worth $9.4 billion to $12 billion.
Despite the position by management, Delta's unsecured creditors committee in its bankruptcy case will play a key role in deciding the airline's future course. The committee had said prior to Wednesday that it was reviewing both Delta's standalone plan and US Airways' buyout offer.
On Tuesday Senate lawmakers said they would more closely examine potential airline mergers, including the hostile bid for Delta. But Parker said there were no concerns about regulatory problems.
"This transaction will not fail on antitrust concerns," he said.