Talks between the International Longshoremen’s Association (ILA) and the U.S. Maritime Alliance (USMX) have stalled. While the talks initially were thought to be moving along, with both sides reaching compromises on key issues, the question of container royalties has stalled things once again.

ILA members currently receive royalty payments based on a container’s tonnage, but USMX officials want to phase that out, halting those payments for new union members. ILA members have rejected that proposal out of hand; president Harold Daggett has directed union locals to prepare for a strike on Dec. 30 at East and Gulf Coast ports should an agreement not be reached.

The National Retail Federation is among several groups calling on President Barack Obama to avert even the threat of a strike. Under the Taft-Hartley Act, a president can suspend lockouts for 80 days should it be deemed vital to the U.S. economy or military.