As we have previously noted, the Court will issue opinions tomorrow. The next opinion day is Monday, January 25. After that, the Court is not scheduled to issue opinions until Tuesday, February 23. The month-long gap results from the break between the Court’s January and February sittings.
The Court could add an additional opinion date. That would have been extremely unlikely under Chief Justice Rehnquist. But in a variety of small ways, the Roberts Court has taken a more pragmatic approach that deviates from certain traditions.
Nonetheless, the Court is an institution that does rest on tradition, and it will have a strong institutional preference for sticking to its usual calendar. The Court is also well aware of the public interest in having the campaign finance case decided, as illustrated by the fact that it held oral argument in late summer, outside the usual argument calendar.
Given that, it would be very surprising if the Court failed to issue a decision tomorrow or on Monday the 25th. I don’t think either is more likely than the other.