There was no immediate comment from the People's Party (OVP), and Nehammer only told reporters after the party's crisis leadership meeting on Sunday that "important and correct decisions" had been taken.
The surprise collapse of three- and then two-party talks aimed at cobbling together a centrist coalition that could serve as a bulwark against the far-right Freedom Party (FPO) after the FPO came first in September's parliamentary election leaves President Alexander Van der Bellen with few options.
A snap election with support for the eurosceptic, Russia-friendly FPO still growing or an about-face in which Van der Bellen tasks FPO leader Herbert Kickl with forming a government are now the most likely options, with only limited scope for alternatives or playing for time.
"It is not an easy situation," Markus Wallner, the governor of Vorarlberg, the westernmost of Austria's nine provinces, told reporters before the OVP leadership meeting at the chancellor's office on Sunday morning.
"I believe we must do everything we can now to avoid sliding towards a national crisis."
Wallner said he opposed a snap election since that would delay the arrival of a new government by months. OVP governors are part of the leadership.
A spokesperson for Van der Bellen said he was due to address the nation later on Sunday. Nehammer crossed the road separating their offices earlier to report to Van der Bellen on the OVP leadership meeting.
Nehammer insisted during and after the election campaign that his party would not govern with Kickl because he was too much of a conspiracy theorist and posed a security risk while at the same time saying much of Kickl's party was trustworthy.
Nehammer's successor will most likely be more open to a coalition with the FPO, which is formally allied with Hungarian Prime Minister Viktor Orban's Fidesz party.
The FPO won September's election with around 29 per cent of the vote, and opinion polls suggest its support has only grown since then, extending its lead over the OVP and Social Democrats to more than 10 percentage points while their support has shrunk.
The OVP and FPO overlap on various issues, particularly taking a tough line on immigration, to the point that the FPO has accused the OVP of stealing its ideas.
The two governed together from late 2017 until 2019, when a video-sting scandal involving the then-leader of the FPO prompted their coalition's collapse. At the state level, they govern together in five of nine states, including in OVP moderate Wallner's Vorarlberg.
The national dynamic is now different because if they were to form an alliance the OVP would for the first time be junior partner to the FPO, making the position of OVP leader difficult and undesirable to many.
