Q: Colorado statute that states a Landlord has the right to leave tenant month to month after lease is up? Thanks.

A: The terms of your holding over (continuing to live there after the original lease expires) are often set forth directly in the original lease itself. There is no statute requiring the landlord to allow you to re-negotiate a new lease. There is likewise no statute that would require landlord to allow you to continue on month-to-month as opposed to week-to-week. The status of your current lease (and your current rights to continue living there) are largely determined by a combination of your previous (original) lease and your (and your landlord's) actions since that lease expired.

It is common for a tenant to stay on month-to-month in the sense that the tenant continues to pay for rent in monthly chunks as it had during the lease. Having paid for a month at a time and landlord accepting it is what the linked PDF below means by saying a month-to-month lease is "implied." Your landlord probably could have, however, required to you to start paying rent weekly in order to create an implied week-to-week lease.

Barring exceptions like landlord's agreement otherwise or accepting your continued monthly payment of rent, your landlord likely would have been within its rights to begin an eviction proceeding (with the required notices, etc.) as soon as your original lease expired and you did not move out. The landlord has no obligation to allow you to sign a new lease.

This is somewhat addressed on page 4 of this PDF from a Colorado.gov site: https://www.colorado.gov/pacific/sites/default/files/Attachment%2010-Landord%20and%20Tenant%20Rights.pdf

The information there may be slightly outdated in that you are now entitled to a 21-day (rather than 10-day) notice to terminate a month-to-month lease. That document might also be helpful in learning about your rights to defend against an eviction by your landlord if it comes to that.