Within hours of the Australian government announcing a “giveaway” budget that Scott Morrison had hoped would propel him to a second term as prime minister, his own party began tearing into him.

Concetta Fierravanti-Wells, a senator from Morrison’s Liberal party, unleashed a blistering 10-minute character assassination, calling her boss an “autocrat (and) a bully who has no moral compass” who was unfit to be prime minister.

The verbal onslaught was just the latest damaging blow landed on Morrison from his own side ahead of the May 21 election. In the past two months, leaked messages from his colleagues have painted him as a “complete psycho”, “a fraud” and a “hypocrite and a liar”. He has also been accused of racially vilifying a rival candidate a decade ago to win a seat in parliament. Morrison has denied the accusation.