California Code, Civil Code - CIV § 8534

(a) A construction lender that objects to the sufficiency of sureties on the bond given with a bonded stop payment notice shall give notice to the claimant of the objection, within 20 days after the bonded stop payment notice is given. The notice shall comply with the requirements of Chapter 2 (commencing with Section 8100) of Title 1.

(b) The claimant may within 10 days after notice of the objection is given substitute for the initial bond a bond executed by an admitted surety insurer. If the claimant does not substitute a bond executed by an admitted surety insurer, the construction lender may disregard the bonded stop payment notice and release all funds withheld in response to that notice.