Germany's Green and Free Democratic (FDP) parties will start coalition talks with the Social Democrats (SPD) on Thursday.
"I have just proposed to Mr Scholz, in agreement with the Greens, to meet tomorrow for a discussion between the three of us, and that will happen", said FDP leader Christian Lindner at a press conference on Wednesday.
It comes after the Greens had earlier announced their coalition preferences.
"We have come to the conclusion that it is now logical to continue discussing with the SPD and the FDP, with a deeper search for common ground," Greens leader Annalena Baerbock told reporters.
Outgoing Vice-Chancellor Olaf Scholz's centre-left SPD narrowly won the country's election on September 26.
The vote left two parties as likely kingmakers: the Greens, who finished third, and the business-friendly FDP, who finished fourth.
Those two parties could team up with either the Social Democrats or the centre-right Union bloc of outgoing Chancellor Angela Merkel for a parliamentary majority.
The Greens traditionally lean to the left, while the Free Democrats in recent decades have mostly allied with the Union. All four parties have held bilateral meetings with each other in recent days.
The Greens' leaders said they have now proposed to the Free Democrats that the two parties go into three-way talks with Scholz's Social Democrats.
That combination appears to offer the "biggest overlaps in terms of content,'' though there are "significant open questions and differences,'' said Greens co-leader Robert Habeck.
He said that the door wasn't completely slammed on a coalition with the Union.
"We have seen the Union really made an effort,'' he added, but his party's differences with the centre-right bloc are bigger.
Questions have been raised over whether the Union is in any state to lead a new government after its candidate for chancellor, North Rhine-Westphalia state governor Armin Laschet, led it to its worst-ever result in the election.