Janša reacted to his comments via his Twitter account: "Zoran Janković will do everything in his power not to stand in the election because he doesn't dare. Four years ago he got 2.97% [of the vote]. Even Alenka Bratušek beat him."
In a suspense-building manner that he had demonstrated in run-ups to general elections before, Janković announced that he would take his decision on how to bid in the election by the 3 May deadline for the submission of lists of candidates when official campaigning gets under way.
Janković said that he already had a list of candidates compiled, assuring reporters that collecting a sufficient number of voter signatures in support of the bid would not be a problem.
Janković won the 2011 general election with his party Positive Slovenia (PS), but failed to build a government coalition, so the role fell to Janša.
However, the Janez Janša government collapsed after only a year in office and Alenka Bratušek as Janković's protegee took over, but resigned a year later after losing a vote for the presidency of his party, which fractured as a result.
Janez Janša: Wikimedia
Janković told reporters that the manner of his involvement in the election would depend on talks with representatives of other left-leaning political parties.
He had already discussed cooperation earlier this month with outgoing PM Miro Cerar as leader of the Modern Centre Party (SMC) and the leader of Social Democrats (SD) Dejan Židan.
His belief is that "we should put aside our egos" to hammer out a deal about "some kind of coalition" or about "forming some common politics".
The effort is in his view needed in order to prevent the victory of Janez Janša and his Democratic Party (SDS), because he believes Janša's policies as PM had been catastrophic.
Janković blamed Janša for selling Mercator, the retailer that Janković used to run, for calling an EU troika to Slovenia and for taking away money from the city of Ljubljana.
"Therefore, my motive is for the left to join forces and win so that we can get a normal government," he said.
Janković answered in the negative when asked whether he had discussed cooperation with Kamnik Mayor Marjan Šarec, who has been at or near the top of opinion polls, but would not rule out talks at some later stage.
If his party should stand in the election, Janković does not plan to be a candidate because he does not see himself in parliament.
Commenting in the criminal procedures running against him, Janković said that he had never been indicted, that he had never been accused of avoiding court mail, was regularly attending hearings, and that all decision taken so far had been in his favour.