ASSUMPTION LETTER

EXHIBIT 4.11

[ASSUMPTION LETTER]

December 31, 2004

Wells Fargo Bank, National Association,

as Property Trustee and Guarantee Trustee

919 Market Street, Suite 700

Wilmington, DE 19801

Wells Fargo Delaware Trust Company,

as Delaware Trustee

919 Market Street, Suite 700

Wilmington, DE 19801

Re: Guaranty Corporation

Ladies and Gentlemen:

By virtue of the merger between Guaranty Corporation, a Colorado corporation (“Guaranty”) and Newco Front Range, Inc., a Colorado corporation and wholly owned subsidiary of Centennial Bank Holdings, Inc., a Delaware corporation (“Centennial”), and the subsequent merger of Guaranty into Centennial, Centennial, as the surviving corporation, does hereby agree, affirm and acknowledge that it assumes all the duties, warranties, and obligations of Guaranty (i) in its role as Depositor and sole Holder of the Common Securities under the Amended and Restated Trust Agreement, dated June 30, 2003 (the “Trust Agreement”), among Guaranty, as Depositor, Wells Fargo Bank, National Association, as property trustee, Well