A spokesman for Ms Gallagher said on Friday "the assumption is completely false'' and he could "100 per cent rule out the claim''.

"She is only seeking preselection for the Senate,'' the spokesman said.

Mr Smith in an interview with The Canberra Times on Thursday ahead of his swearing in on Monday claimed there were rumours that Labor pressured Ms Gallagher to stay in the Senate to shore up leadership of the Left in the Upper House rather than seek preselection for the Lower House.

"I think there's some disappointment Katy is not running for the third House of Reps seat because the other view coming back to me is that she would be an ideal member there, it's right in her heartland in the inner north and inner south,'' he said.

"Party members are still hopeful that is an outcome we can achieve. They don't want a messy preselection. I think there will still be discussions over the coming weeks.

"As Harold Wilson said, 'a week is a long time in politics'. A couple of days can be a long time and the game sort of changes. ''

Mr Smith also said the "opportunities available to Katy in the House are pretty enormous''.

Mr Smith said he was never formally asked to step aside to clear the way for Ms Gallagher's return to the Senate following her ousting from Parliament by the High Court over the citizenship bungle. But his wife, Liesl Centenera, said she was hurt by calls from people such as former chief minister Jon Stanhope that he should quietly slip away.

"I wasn't annoyed, I was mystified more than anything else,'' she said.

"This was the second time that David had run in the second Senate spot and while you never expect anything to ever come of it, I would have thought that was a clear indication that public office was something that he was clearly interested in and clearly aspired to...

"I would have thought when the opportunity arose, people would expect him to take it, and take it in full and take advantage of that opportunity entails, not matter how long that ends up being.

"So maybe there was a level of hurtfulness there. But I think anyone who knows David knows he wouldn't be of the mindset to step aside.''

Mr Smith, 48, the former ACT director of the union Professionals Australia, is learning fast about being in the public eye, his hackles raised by online slights about his Catholicism and union background and suggestions by Ms Gallagher he may be more closely aligned to the conservative opinions of ACT Liberal Senator Zed Seselja.

"It may not be meant, but it's still casual bigotry. The Catholic Church is a broad church. It would effectively be like saying Tony Abbott, Malcolm Turnbull and Bill Shorten agree on everything because they went to Catholic schools,'' Mr Smith said.

"....It happens in Canberra almost every time someone with a Catholic background puts their hand up for preselection and it's actually getting a bit tired. Let's have a deeper conversation about what that might mean. What it might mean is that my position on asylum seekers might actually be more similar to [Labor MP] Ged Kearney, unsurprisingly another person with a Catholic upbringing, and may not be that close to Zed's.''

Mr Smith, a father of three, and former Marist College and ANU student, will be surrounded by family and friends for his swearing in at 10am on Monday, when he will be brought into the chamber flanked by Labor senators Penny Wong and Don Farrell. His voice catches when he says one person he will be thinking of is the late Terry Connolly, a former Labor attorney-general and Supreme Court judge, who died of a heart attack aged 55 in 2007. Mr Smith was a self-described "Young Turk'' of the party when Connolly was in the Assembly and found him inspirational.

"I think Terry Connolly was one of Labor's great opportunities missed. He should have been chief minister,'' Mr Smith said.

"He really made it very clear you have to be motivated by the right reasons and be serious. How can you made a difference for the people you represent?''

Mr Smith said future issues for Canberra would be funding freezes for the ANU and University of Canberra. A resident of Farrer, he also believes the south of Canberra could benefit from a university campus.

"If you come from the south of Canberra, there's no university presence at all,'' he said.

"If you look at some emerging data around - who goes to university? Who stays at university? - if you don't live close to a university, it's less likely you will go and attend a university.  Back in 2015, there were some discussions around how could we revitalise Woden and perhaps look at some kind of health university hub, that's something I'd be keen to talk to Chris Steel and Bec Cody, the Woden MLAs, and Andrew Barr, about actually doing something along those lines.'

"I think we've got a real concentration of university campuses in the inner-north, in particular, and I think we need to open up those opportunities.''

Mr Smith also maintains he is the "best-placed person out of the whole federal Labor team in Canberra'' to ensure campaigns about workplace relations translate into government action.

"[It's] one of the reasons I'm pretty determined to fight on and want to be the senator for the ACT representing the Labor Party,''he said.

He says wage stagnatation, protracted pay disputes and people being pressured to be contractors were all issues he wanted to pursue.

"The real honour for me [in my career to date], has been trying to help out really good people in difficult circumstances who are just trying to ensure they get treated with fairness and equity at work. If that's what a union hack is, I'm happy to be called that any day of the week,'' he said.

Ms Centenera and Mr Smith have been married for 17 years. They met at at the Department of Employment and Workplace Relations (he in the public sector industrial relations branch and she in the legal branch). Ms Centenera laughs when she says she couldn't stand him in the beginning. Now they are a tight team, she a definite asset, with her good humour and forthrightness. Ms Centenera says her husband's caring nature will help his political career.

"I think being a real family person and that translating into being a carer of the constituency,'' she said.

"David is doing the CEO sleepout next week. I sit on a lot of not-for-profit boards, we make the children fold the newsletters for Neighbourhood Watch. We are very, very committed to the community and bettering the community and connecting the community and hearing what they need and seeing if we can contribute to that. I suppose it's that reservoir of care that would be the biggest thing I see in him.''