He was hoping for a 67-seat coalition, but the hard-right Yisrael Beteinu party apparently refused to join. (Unclear if that was for ideological reasons, or because they demanded cabinet posts he has already promised to other parties.)
This is problematic for Bibi for two reasons: (1) A 61-seat coalition is very unstable-- it's the bare minimum for a Knesset majority, so any single party in the coalition can end the government and require new elections simply by dropping out at any time. (2) He got to 61 only by including the two ultra-Orthodox parties (Shas and UTJ), who were not in his prior coalition. They will doubtless insist on restoring the draft exemption for students at their Yeshivas, a controversial policy that is not only anathema to Israel's left, but also very unpopular with the secular and moderate-religious elements of the center and right, who see it as favoritism at best and a national-security threat at worst.
So, for two reasons, this may prove to be a very short-lived government.
Yisrael Beytenu will functionally support this government, and there is already talk that it will join the government formally.
There was never going to be any right-leaning government without the religious parties.
What is the deal with the hard right? Can’t they see Bibi is better than an Obama backed PM?