I think it is pretty obvious, though not certain, that the leak came from the left. The left will stop at nothing to get their way.
Sanders is correct; however, in his statement of how to change U.S. law. The problem with the Roe decision was it did not follow the procedure outlined by Sanders. On the other hand, a law-making on an issue like abortion should and must be bipartisan in nature including both Democrats and Republicans. That will require negotiations and compromise. That is how our system is built. It is built that way to prevent one-sided laws created by a simple majority that half the country is against.
I don’t believe the Democrats have 50 votes for an effort anyway. Either for ending the filibuster or for a national abortion law.
The abortion fanatics will be out in force and the irresponsible media and politicians will use them for political advantage. I believe the country has moved on this issue and the old Bill Clinton position is the current fashion, “legal, safe, rare.” But it will go to states for decisions.
In case you doubted that the issue would be demagogued by irresponsible politicians, Here are the Democrat leaders of the house and senate (Democrats control all three branches of government at the moment) issuing a joint statement:

Yes, the gates of hell have opened and Republican devils in the guise of Hitler have issued forth to prevent minority women from killing their unborn children.
BIDEN CALLS FOR ELECTION OF ABORTION ADVOCATES
Abortion is everything now. Remember what abortion is.
Abortion is the killing of an unborn child.
Abortion has become a cult religion for the left.