Bill English rang Winston Peters over the weekend but hasn't had a response - and says despite his own keenness to get negotiations under way this week that now looks unlikely.
In his regular round of Monday morning interviews English revealed he had tried to contact Peters and at several times stressed his view that Peters was leaving it late to begin talks.
"There wasn't a response but I think that just means Mr Peters is sticking to the timetable he outlined last week," English told Newstalk ZB.
"We would like to see some preliminary discussions take place this week but that looks unlikely."
Peters told TVNZ this morning that by the time he was aware that English had made a call, and had left a message, it was too late to return the call.
The NZ First leader says he will return English's call this morning.
Peters has said he will wait until the special votes are counted this Saturday before finalising any agreement, although he has indicated preliminary talks could start before then. He has said he wants to have a decision made by next Thursday.
This morning, English said that timeline "looks a bit of a stretch". National would this week continue preparations for what looks like it will now be a "pretty pressurised" process, including for New Zealand First.
"That looks to us to be quite a challenge."
National won 58 seats, Labour and the Greens won 52 combined, and New Zealand First won 9.
In a 120 seat Parliament in which 61 is required for a majority, Labour and the Greens and New Zealand First have only 61. The special votes - some 15 per cent of the total - usually favour the Greens and Labour.
However, English today played down the impact the special votes could have, saying even if Labour and the Greens gained some seats the basic permutations remained the same.
"Even if National dropped back a bit we still have significantly more seats...and the combinations remain the same," English said.
"This would essentially be a new government designed to last for a number of terms and you want to get the basis for that clear at the start."
English said National received a stronger vote than the other parties expected.
"The public want to see a continuation of the economic management."
In a press conference held by Peters last week the New Zealand First leader rubbished any notion that National had any sort of "moral authority" because it was the largest party.
Asked if he believed his party did have a moral authority ahead of talks, English said National was in a position to form a Government.
"We have the largest number of seats by enough of a margin that we could form a Government with one other party.
"It takes all three of them [Labour, Greens, NZ First] to change the Government..".
English said no approach had been made to the Green Party about a deal.
"We will see what happens there this week."
He said the Green Party had consistently said a vote for them would be to change the government.
National would be prepared to walk away from negotiations if the price demanded was too high.
"You always have to be prepared to walk away from a negotiation...but I think the party leaders have a reasonably good idea of their relative weight in negotiations and that's how the public would see it - someone with a small proportion of the vote doesn't get to dictate all the policy."
Asked if he believed Labour would "throw the kitchen sink" at negotiations, English said they faced a complex situation in having to get the Greens and NZ First to agree on a deal.