Middlesex is in the weight room, frantically building muscle mass.

Assemblyman Andrew Zwicker (D-16) is not yet on the cold slab, a source insisted.

Moreover, state Senator Joe Cryan (D-19) should occupy a turret in the Middlesex fortress, even though he’s from Union.

That’s five, maybe six senators.

If Senate President Steve Sweeney (D-3) topples from the senate throne, Middlesex still has an edge in deciding his successor, sources say.

Yesterday there were 25 Democratic Party senators. On the other side of December 24 makes 13 the magic number to succeed Sweeney.

If you add Cyan, Middlesex County Democratic Committee Chairman Kevin McCabe starts – even on a bad day – with five.

He doesn’t want to alienate North Jersey by relying on those remaining South Jersey senators (Beach, Madden, Cruz-Perez, Singleton), so he grabs – for argument’s sake – handfuls from both camps (Ruiz, Gill, Stack, etc.), maybe Senator Nick Scutari too (in exchange for letting him keep judiciary) to give the edge to whomever he decides.

Senator Joe Vitale?

Maybe.

Or Cryan himself.

“McCabe is the only chairman who starts with five,” the source said. “When he sits across the table, he can look you in the eye with five.”

Other chairs have a more challenging position

Bergen: Johnson, Lagana, Sarlo.

Hudson: Stack, Sacco, Cunningham.

The Hudson senators especially, like Codey in Essex and Turner in Mercer, are personalities who won’t merely follow the herd or fold into the combines of a machine.

Would the other counties allow Cryan and Speaker Craig Coughlin (D-19) to occupy power?

Or would Cryan’s ascent on behalf of Middlesex require Coughlin to step down to empower someone from the north?

Would Essex be in the game for governor, or require governor and speaker?

Would any of the other senators from the loose change counties be in a position to hold out for deals?

In the inimitable words of South Jersey Power Broker George Norcross, “You can never be without one house.”

As it turns out, Middlesex wants to stick as scheduled – pre Sweeney collapse – with Coughlin as speaker, which lessens the likelihood of the senate president emerging from Middlesex but with Zwicker heading for victory, increases Middlesex’s power projection platform.