Lambton's decision was based on a desire to step out of the media spotlight and resume his "normal life," according to an E! News source.
However that doesn't mean The Bachelor producers have given up on landing The Bachelorette runner-up and viewer favorite.
"The producers really want Chris to be the guy. They're hoping they can convince him... This definitely isn't dead yet," the source said.
"All of our best Bachelors have been hesitant at first."
Lambton's reported decision is consistent with his prior comments about whether he'd be interested serving as the star of the next The Bachelor edition.
"Honestly, it's something that I'll have to think long and hard about because it was hard watching, you know, so much of my personal life and intimate details of like dating and love on TV," he told reporters about the possibility earlier this month.
"It's hard to share that kind of thing with many millions of people who watch the show. So, I mean, it's definitely something that I'll have to, you know, really, really think about. I'm not really sure if I want to share all that again."