Wentworth by-election tight and vital: PM

Scott Morrison has kicked off the campaign to retain the seat of Wentworth, saying it will be a very tight contest.

Prime Minister Scott Morrison says the Wentworth by-election is crucial to the future of the country.

Mr Morrison visited the Sydney seat - formerly held by Malcolm Turnbull with a margin of 17 per cent - with the newly preselected Liberal candidate Dave Sharma on Friday.

"This will be a very, very, very tight contest ... and this is a very important by-election for the future of our economy, for the future direction of the country," Mr Morrison told reporters.