Poner candado contra alguien

Poner candado contra alguien
 

The headline of an article in La Jornada reads "San Lázaro pone candado contra nuevas bancadas".
I found out San Lázaro is the name of the place where the legislative branch meets, so that cleared that up, but I thought poner candado meant to put a lock on something.
The article seems to say the legislature put limits on its new members.
Can poner candado have figurative meanings as well?

It's election time soon for the Mexican Congress. The "bancadas" are groups of legislators belonging to the same political party (there are 10 political parties in Mexico).
The sentence means that the current legislators created new rules against the actions of the new members. Particularly, they don't want changes in the existing political groups.

In Mexican news one finds often "ponerle candado a (alguien/algo)", which means to set a restriction against someone or something, as if you put an animal in a cage.

Metaphor is a powerful tool in communication, so there are few literal phrases which can't also be used figuratively.

The headline could perhaps be translated San Lázaro locks out new formations.