This means that Reform has not ruled out being either in a ''coalition of equals'' with Centre, currently in second place and about 10 mandates behind Reform, or with the fourth and fifth place parties, the Social Democratic Party (SDE) and Isamaa. The latter two are currently in the coalition and were Reform's previous coalition partners from 2015-2016, so may yet find themselves being mummy bear and baby bear, to Reform's daddy bear.

The only party ruled out, a statement which Ms Kallas and several other leading Reform members have already made, is the Conservative People's Party of Estonia (EKRE).

''EKRE is not an option for us. We have excluded cooperation with them from the outset," she said, in the ETV studios.

The most important things are principles, rather than maths, though two parties are certainly more workable than three, she said.

However, she was clear to point out that Centre would have to take a long look at its program, if it were to enter into partnership with Reform.

''If we look at our manifestos, we can see strong differences with Centre in three areas: taxation, citizenship and education,'' she said.

Reform/Centre red lines

Reform has long criticised Centre's tax policy and tax reform is a central plank of its platform. Some key Centre players such as Yana Toom have made citizenship for the so-called ''grey passport'' holders a clarion call, and not something which people should, for instance, have to take a language test to attain, as under current law. Centre favours bilingual (ie. Estonian and Russian) education in regions where needed; Reform wants all-Estonian education.

''We're keeping all our coalition options on the table and talking things through. The negotiations are just beginning,'' said Ms Kallas.

The party board is set to meet at 09.00 on Monday morning to discuss matters, by which time the full electoral result will be known.

Kaja Kallas added that the two smaller parties noted above, Isamaa and SDE, have more commonalities with Reform than Centre does. Indeed, with the latter it is more a case of red lines, she said.

She added that she did not take Isamaa and SDE's abandoning of Reform for Centre, in November 2016, personally.

Kadri Simson: We are Reform's least favoured choice

Meanwhile economic affairs minister Kadri Simson (Centre) has said that her party would be Reform's least favoured choice for coalition partnership.

She added that being in opposition was also a worthwhile place to be in, with plenty of work to be engaged in.

With Estonia 200, Free, Greens and Richness of Life all failing to pick up seats, the XIV Riigikogu will be a five-party affair.