WASHINGTON - A proposal that could shape how much money is paid to victims of the May 12 Amtrak derailment in Philadelphia is facing legislative and political stumbling blocks as a key deadline looms in Congress.

The plan would raise to $295 million the liability cap for railroads - hiking by $95 million, or nearly 50 percent, a limit on damages that critics say is outdated and insufficient for an incident that killed eight and injured hundreds of passengers.

But the proposal, which easily passed the Senate as part of a bipartisan transportation bill this year, is now part of crunch-time negotiations on a House-Senate compromise, and under scrutiny by rail lobbyists and House Republicans, including a powerful Pennsylvanian.

Without the change, according to the victims' lawyers, compensation could be trimmed - potentially shortchanging people who lost parents and spouses or sustained life-altering injuries, including paralysis, damaged organs, and severe fractures.

"People are going to be getting less than full justice," said Robert Mongeluzzi, a Philadelphia lawyer representing several victims, including two whose medical bills have topped $1 million.

The fight, largely playing out behind closed doors, is hurtling toward a conclusion: Lawmakers hope to introduce a final Senate-House transportation package Nov. 30 and pass it by Dec. 4.

Sen. Bill Nelson (D., Fla.), who had proposed raising the cap to $500 million, pointed to the Philadelphia wreck in arguing for the increase at a hearing this week.

Commuter railroads have pushed back, saying the change could be expensive, and representatives from state agencies such as SEPTA worry that the federal law could trump state laws under which they face even lighter caps.

Pennsylvania law, for instance, limits SEPTA's liability to $1 million per incident, no matter how many people are hurt.

SEPTA'S worries

Rep. Bill Shuster, the Republican from Blair County who chairs the panel negotiating the transportation compromise, cited SEPTA's worries when asked about the liability cap this week.

"There's several states that have their own provisions, and I'd like to see that stand," said Shuster, the chairman of the House transportation committee.

Tom Kline, a Philadelphia lawyer representing Amtrak victims, called the argument "bogus" and "an excuse to say no."

He and Mongeluzzi represent 30 of the approximately 70 people who filed legal claims after the May derailment of Amtrak Train 188. The exact cause of the crash is unclear, but Amtrak has conceded human error and said it would not contest its liability.

Regional agencies such as SEPTA already operate under their state limits, not the federal cap, Kline said, adding that a few words inserted into the new legislation could clear up any confusion.

Congressional aides close to the negotiations, however, say the new limit in the Senate bill would apply to all rail lines - including regional ones - which has prompted some of Shuster's objections.

SEPTA wants to settle the confusion.

"So far, we're told that it's not meant to apply to Pennsylvania or other railroads like SEPTA," said the agency's general counsel, Gino Benedetti, who said the agency would not oppose a change in the federal cap if the conflict is resolved. "Our pushback to them is: Please make that clear in the statute so we don't have to risk spending lots of money and lots of time litigating the issue down the road."

Keeping its liability lower allows SEPTA to spend money on capital improvements and infrastructure, Benedetti said.

'Vetting all the issues'

A Shuster spokesman said that the potential conflict between state and federal law was only "one of a number of concerns he's heard" about the liability cap - and that the chairman was still "vetting all the issues."

Lawyers and some victims from the derailment have written to members of Congress describing their injuries. Kline and Mongeluzzi said they had pressed lawmakers from northeastern states where the victims live.

Rail lobbyists are also pressing.

"There is little evidence that the current cap is insufficient," said a letter from the American Public Transportation Association, which represents commuter rail lines. "Major increases in liability requirements may lead to substantial and unnecessary added costs for publicly funded commuter railroads."

An Amtrak spokeswoman said the agency was confident Congress would balance "all interests involved."

The cap was enacted in 1997 to help prevent big financial hits to cash-strapped rail lines. Critics say it unfairly establishes a limit on train passengers that is not in place for other forms of transportation.

They also point out that it has not been raised in the nearly two decades since its creation.

In that time, though, only one case has seen the cap affect a judgment. A California judge found that victims in a 2008 rail crash there were entitled to $264 million but he could only distribute $200 million, and had to cut short some of the payouts to deserving victims.

Nelson's plan calls for raising the cap to account for inflation since 1997. It would allow automatic increases every five years.

The House did not change the cap in its transportation plan.

The differences between the packages are being worked out by a 41-person House-Senate committee, which held one hearing but otherwise will operate out of public view.

The liability issue is a small piece of the $325 billion bill affecting railroads, highways, and safety laws. During a two-hour hearing on that bill Wednesday, it came up only twice.

The House is "in a different place" than the Senate on the liability limit, said Sen. John Thune (R., S.D.), who heads the committee that oversees rail.

The outcome will hinge on the give and take over an array of other items in the bill. "It could be, like a lot of these things, that it kind of gets negotiated out, ends up somewhere in between," Thune said. "There's a lot of interaction with other issues."

@JonathanTamari