It’s also possible that the expanded credit is struggling to overcome Americans’ deep-seated beliefs about who deserves government help and who does not. Broad evidence suggests many are skeptical of programs that provide cash without conditions.

Parents who do not pay income taxes can access the credit. While many experts doubt the program nudges large numbers of recipients to leave the work force, some disagree — and polling suggests Americans overwhelmingly support work requirements for adults who receive government benefits in some or all cases. (Social Security and Medicare, nearly universal programs that Americans pay into via taxes before receiving benefits later in life, are rare exceptions, Professor Campbell said.)

An August YouGov survey conducted for American Compass, a conservative think tank, found that increasing the value of the credit, making it available monthly and sending it to households without a working adult were all popular policy changes, but that sending it to nonworking families was the least popular of the three. And most Republicans, independents and voters without a four-year college degree whose households earn between $30,000 and $80,000 did not favor permanently sending payments to nonworking families.