A father has confessed to trying to kill his two-year-old son in a car crash.

A toddler has been left in a critical condition after his father attempted to kill him in a car accident.

Telling police he was unable to handle the pressures of parenthood, 29-year-old Nathan Weitzel placed his two-and-a-half-year-old son Isaiah in the car without a seatbelt.

He then drove down a suburban street in Colorado, USA, at speeds of up to 120km/h, hitting several cars along the way.

“I was trying to kill my son,” Weitzel told police following the crash.

Nathan Weitzel following the crash. 9News.

The incident occurred just before midday on August 21 after Weitzel drove his son to a park.

A court statement said he then "left the park and drove around looking for a good place to crash the car and kill his son."

Police were told Weitzel deliberately didn't put Isaiah in a child seat and left him unbuckled.

The father has since admitted to using cocaine before the crash.

"The reason he wanted to kill Isaiah was because being a father was a big responsibility and he did not think he was man enough to raise a child," an investigator told KHOU.

Weitzel, the father who tried to kill his son.. Source: 9News.

And while Isaiah has miraculously survived the crash, close to half of his body is in a cast and his movement has been severely limited. It is not yet known if there will be long-term damage.

Isiah's mother Nacy Lopez, who is separated from Weitzel, told 9NEWS, "I don't understand why or how he could do something like this, but I'm hoping Isaiah recovers soon people pray for us and for my son to get better."

Isiah recovering after the crash. Source: 9News.

Lopez described her son as a "really caring boy," adding, "he's really compassionate with other kids."

When asked about her ex-partner, Lopez said, "He's in the place that he should be. He needs to be in jail for a long time."

Weitzel is being held behind bars after being charged with attempted first-degree murder, child abuse, assault, criminal mischief, possession of a controlled substance and vehicular assault.