He cited The Inquirer's report that more than a dozen witnesses in criminal cases had been murdered in Philadelphia since 1999.
Casey's measure would apply the current federal penalty for attempted murder - up to 30 years' imprisonment - to the crime of witness intimidation.
The proposal would also allow state and local governments to compete for federal funding to relocate or otherwise protect witnesses in local cases. The government would pick up three-quarters of the expense of the best proposals, he said.
Casey first introduced a bill to federalize the crime of witness intimidation in February of last year. The measure did not make it out of committee and died at the end of the session.
On Friday, he said the failure of his proposal had not reflected active opposition, but the ascendancy of other priorities.
Others in Congress have pushed without success in recent years for measures to provide extra federal help to fight witness intimidation. When in office, Sen. Arlen Specter (D, Pa.) also introduced legislation to make intimidation a federal crime.
U.S. Rep. Elijah Cummings (D., Md.) has been pushing for almost a decade for more federal funding to relocate witnesses. His proposal passed the House overwhelmingly but never won passage in the Senate.
In a notorious attack in Baltimore in 2002, a family of seven - two parents and five children - was wiped out when a firebomb was thrown into their house after the children's mother testified against drug dealers.
In Philadelphia, alleged drug kingpin Kaboni Savage is on trial in federal court for racketeering and murder charges arising from a dozen deaths, including a 2004 firebombing that left six people dead. Prosecutor say the six were slain to retaliate against a witness.
Contact Craig R. McCoy at 215-854-4821 or email@example.com or follow @CraigRMcCoy on Twitter.