Opposition Republicans are using the delaying tactic at a record-setting pace.
"The numbers are astonishing in this Congress," says Jim Riddlesperger, political science professor at Texas Christian University in Fort Worth.
The filibuster, using seemingly endless debate to block legislative action, has become entrenched like a dandelion tap root in the midst of the shrill partisanship gripping Washington.
But the filibuster is nothing new. Its use dates to the mists of Senate history, but until the civil rights era, it was rarely used.