fall in line

1. Also, fall into line. Adhere to established rules or predetermined courses of action. For example, This idea falls in line with the entire agenda, or It wasn't easy to get all the tenants to fall into line concerning the rent hike. A related term is bring into line, meaning “to make someone fit established rules,” as in It was her job to bring her class into line with the others. These terms employ line in the sense of “alignment,” a usage dating from about 1500.

Example Sentences

“What is truly incredible is the extent to which the GOP has fallen in line,” Levinson said.

From Salon

Five days later, though, it appears the GOP has once again fallen in line behind their leader.

From Salon

Newsmax is also falling in line, referring to Maxwell as a “victim” herself.

From Salon

But already, they appear to be falling in line.

From Salon

A majority of Republicans have fallen in line behind the president.

From BBC