Kings of Leon Push for Lead Singer to Seek Treatment for Alcohol Abuse As Summer Tour Canceled

Kings of Leon perform on the Today Show. (AP)

NEW YORK -- Kings of Leon bandmates are urging lead singer Caleb Follo will to get treatment for alcohol issues after the rock group was forced to cancel their US summer tour.

"They are trying to get Caleb to go to rehab. It is mostly for alcohol," one source told Us Weekly Tuesday, while another source described his drinking as "out of control ... It's a dark demon he has been fighting for awhile."

The group announced Monday they were bowing out of more than 20 summer performances in the US "due to Caleb Followill suffering from vocal issues and exhaustion."

Followill, 29, is the lead vocalist for the Grammy Award-winning band made up of his brothers Nathan and Jared and cousin Matthew.

News of the canceled tour came days after the frontman abruptly ended a weekend concert in Dallas, citing the extreme heat

His brother Jared admitted at the time that "there are internal sicknesses & problems that have needed to be addressed ... There are problems in our band bigger than not drinking enough Gatorade," in a tweet after the Texas fiasco.

Caleb Followill is recently married -- having wed model Lily Aldridge, 25, in May.