POWER OF ATTORNEY
For Executing Forms 3, 4 and 5 and 144

     Know all by these present that the undersigned constitutes and
appoints each of Randall J. Erickson, Lynn M. Floeter, Marie A. Radtke
and Jodi Rosenthal, acting individually, as the undersigned's true and
lawful attorney in fact to:
(1)	execute for and on behalf of the undersigned Forms 3, 4 and 5
in accordance with Section 16(a) of the Securities Exchange
Act of 1934 and the rules thereunder;
(2)	execute for and on behalf of the undersigned notices on Form
144 in accordance with Rule 144 under the Securities Act of
1933;
(3)	do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to complete
the execution of any such Forms 3, 4 or 5 or Form 144 and the
timely filing of such forms with the United States Securities
and Exchange Commission and any other authority; and
(4)	take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorney-in-
fact, may be of benefit to, in the best interest of, or
legally required by, the undersigned, it being understood that
the documents executed by such attorney-in-fact on behalf of
the undersigned pursuant to the Power of Attorney shall be in
such form and shall contain such terms and conditions as such
attorney-in-fact may approve in his or her discretion.

The undersigned hereby grants to each such attorney-in-fact full
power and authority to do and perform all and every act and thing
whatsoever requisite, necessary and proper to be done in the
exercise of any of the rights and powers herein granted, as fully
to all intents and purposes as such attorney-in-fact might or could
do if personally present, with full power of substitution or
revocation, cause to be done by virtue of this Power of Attorney
and the rights and powers herein granted. The undersigned
acknowledges that the foregoing attorneys-in-fact, in serving in
such capacity at the request of the undersigned, are not assuming
any of the undersigned's responsibilities to comply with Section 16
of the Securities Exchange Act of 1934 and the rules thereunder or
Rule 144 under the Securities Act of 1933. This Power of Attorney
shall be a durable power of attorney and shall not be affected by
subsequent disability or incapacity of the undersigned.

IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of this 18th day of April, 2021.

/s/Andrew J. Harmening