The Morrison government has taken another blow in the aftermath of last week's leadership spill, with Liberal backbencher Julia Banks declaring she will quit Parliament at the next election in a decision that puts a key marginal seat in play.

Ms Banks blasted the "vindictive" behaviour of the Liberal Party's factional powerbrokers in a thinly veiled attack on those who pushed for Peter Dutton to replace Malcolm Turnbull in last week's chaotic spill.

Julia Banks will not contest her marginal Victorian seat in protest at the dumping of Malcolm Turnbull. Credit:Eddie Jim

Her decision is a devastating blow for the government because its survival depends on its ability to hold ground in seats such as her electorate of Chisholm in suburban Melbourne, which she won by a margin of just 1.6 per cent at the last election after leaving a successful career in business.

"I have always listened to the people who elected me and put Australia's national interest before internal political games, factional party figures, self-proclaimed power-brokers and certain media personalities who bear vindictive, mean-spirited grudges intent on settling their personal scores," Ms Banks said in a statement.