A bipartisan group of senators on Wednesday called for the Government Accountability Office to conduct a comprehensive investigation into all 56 regional offices of the Department of Veterans Affairs to address mismanagement issues that caused delays in processing veterans' disability and pension claims.

The senators plan to introduce legislation that would mandate the investigation, according to the Associated Press.

Recent findings of mismanagement at the VA's worst-performing Philadelphia regional office - such as piles of mishandled and neglected mail, improper payments, long pension claim wait times, altered quality reviews, and manipulation of dates to make old claims look new - suggest there may be department-wide problems, the senators said.

"The VA system again finds itself engulfed in another scandal," said Sen. Dean Heller, R-Nev., co-chairman of the Senate's VA backlog working group, the AP reported.

Heller said that VA hospitals across the nation are being mismanaged, which proves "it is time for an overhaul of the entire system."

Sen. Bob Casey also expressed concern that the problems existed throughout the entire VA system rather than just in Philadelphia.

"It's simply unacceptable to have a veteran with disability wait hundreds of days for their claim to be resolved," he said, reported AP.

According to the VA, there are currently 161,000 disability and compensation claims on backlog, meaning they have been pending for more than 125 days, while in March 2013, the VA said it had 611,000 in backlog. The VA inspector general has questioned the accuracy of that data, though, the AP said.

An audit released last month found that 31,000 benefit claims were pending an average of 312 days, rather than five, due to "mismanagement" at "various levels." The government also paid out millions because the office failed to keep track of duplicate records.

The Senate report said that the 10 worst-performing regional offices in terms of wait times were Baltimore, Md., Jackson, Miss., Reno, Nev., Philadelphia, Penn., Los Angeles, Calif., Chicago, Ill., Oakland, Calif., Indianapolis, Ind., Boston, Mass. and St. Petersburg, Fla., AP reported.

The audit found doctored data, among other problems, at five of the ten offices.