Mr Key will later today give a general idea of the parties National could deal with in post election talks.
"Today will be this is who we broadly think we can chat to," Mr Key told TV3's Firstline this morning.
However, he would not entertain the idea of talking to Mr Dotcom's political vehicle.
"He's not a party is he? He hasn't actually formed one, it's a concept. But I put him in that grouping of a whole bunch of sort of random, minnow kind of people. Whether it's Bill and Ben or McGillicuddy Serious or a bunch of other people, he's in that grouping."
Mr Key indicated that despite its most recent problems stemming from the electoral finance charges faced by current Epsom MP and Leader John Banks, ACT remained a serious prospect for a post-election deal.
He was positive about former ACT MP and current party President John Boscawen declaring his intention to seek the party's nod to stand in Epsom.
"I've worked with him, I've appointed him as a minister. He's a very predictable, thoroughly decent man, John. He's got a good brain on him and there are no surprises with the guy.
"Will he win the selection for ACT? I don't know. But if he does, could we work with him? My guess is yes."
Mr Key said he didn't think it was likely he would go through the "cup of tea" ritual with ACT's Epsom candidate this year or other potential political partners as he did three years ago with Mr Banks to signal National's endorsement of him to voters.
"What is more likely that we're a little more precise, if you like, about that.
"We're more likely to say National could form a Government with these parties if they're returned to Government we think it's more likely this is the pathway they would have to follow and on that basis give a clearer indication."
Mr Key is expected to give his "topline indication" of potential suitors at his post-Cabinet press conference at 4pm.
- Adam Bennett of the New Zealand Herald
