WASHINGTON (AP) — Despite frequent mass shootings, Congress has proved to be unable to pass substantial gun violence legislation, largely because of resistance from Republicans.

But a bipartisan proposal by Sens. Lindsey Graham, R-S.C., and Richard Blumenthal, D-Conn., is gaining momentum following weekend mass shootings in Texas and Ohio that left 31 people dead. The emerging plan would create a federal grant program to encourage states to adopt "red flag" laws to take guns away from people believed to be dangers to themselves or others.

A similar bill never came up for a vote in the GOP-cont...