Paul Ingrassia, the nominee of President Donald Trump to lead a key US federal watchdog agency, has dropped out after the emergence of a series of offensive text messages that he allegedly sent.

Ingrassia, 30, said he was withdrawing his name to lead the Office of Special Counsel (OSC) "because unfortunately I do not have enough Republican votes at this time".

Several Republican senators had warned they would vote against Ingrassia after Politico reported earlier this week that he had sent messages to a group chat in which he allegedly described himself as having a "Nazi streak".

A White House official confirmed to BBC News that Ingrassia was no longer Trump's nominee for the role.

As an independent federal agency, the OSC seeks to protect government employees who blow the whistle on prohibited practices.