WASHINGTON (Reuters) – The Republican-controlled U.S. Congress is poised to allow tax credits to lapse for 24 million Americans, as a Dec. 31 deadline approaches with no sign of a health care compromise after the Senate failed to advance dueling proposals on Thursday.

In back-to-back votes largely along party lines, Democrats and Republicans blocked each other’s bill, leaving Congress no closer to reducing healthcare costs for many Americans, with premiums set to spike on Jan. 1. 

The Republican bill by U.S. Sens. Bill Cassidy of Louisiana and Mike Crapo of Idaho would send up to $1,500 to individuals earning less than 700% of the federal poverty level — about $110,000 for an individual or $225,000 for a f...