The ACT Liberal Senate candidate and wife Ros welcomed their fifth baby on Monday night, a daughter, Grace; new sister to Michael, Tommy, William and Olivia.

Mr Seselja looked the seasoned pro, although he claimed he was ''out of practice'' with newborns, with Grace 13 years younger than her eldest brother.

Despite the arrival of number five just days before the election, Mr Seselja was a picture of relaxation, doting over his sleeping newborn with obvious affection.

''It's a crazy time for a baby to come,'' he said, noting her timing could have been worse as Grace was already overdue. ''We'd seen the doctor [on Monday] and she was talking about inducing on Friday, which would have been interesting.''

Instead, Mr Seselja got the call from his wife at 8.20 on Monday night, just before he was due to speak at a forum. He made his apologies and promptly left, with little time to spare before their daughter was born at 11.15pm, weighing in at a chunky 9 pounds 15 ounces (4.5 kilograms).

Election duties will be scaled back as Mr Seselja juggles daddy duties while his wife remains in hospital for a few more days. ''The grandparents will be helping out, so I will resume campaigning [on Wednesday] but probably in a limited way … I'm on dad duties and I'll be in the hospital two or three times and just saying g'day and getting to know this little girl.''

Campaigning was far from his mind as he cuddled Grace; on the agenda was her first bath, something he was eager to do. ''I did the first bath with most of them - I did the first nappy for Michael,'' he said, having escaped nappy duty so far with the latest addition to his brood.

''We bought a four-wheel-drive a little while ago and that's got eight seats … we're not planning on filling it, but there is a spare seat,'' he said.

A beaming Mrs Seselja was looking forward to her ''break'' in hospital before heading home with the family.

''They're all at school now, so it will be nice to be just [Grace] and I during the day,'' she said.