Given their narrow majority, Senate Republicans prefer to let Andrew Wheeler continue as acting administrator rather than squeeze in another confirmation fight before the November mid-terms.
The Trump administration said on Tuesday that it will release reunited migrant families with ankle bracelet monitoring, backing off from efforts to detain them indefinitely.
The seeds of the Trump movement were laid more than 50 years before his bid for the White House, after Southern Democrats suffered a series of voter defections.
Republicans are settling in to be the minority party in power for many years to come, and they are increasingly testing many voters' faith in the system.