<Page>
EX-99.CERT
CERTIFICATIONS PURSUANT TO
SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002
I, Thomas S. Schreier, Jr., certify that:
1. I have reviewed this report on Form N-CSR of American Municipal Income
Portfolio Inc.;
2. Based on my knowledge, this report does not contain any untrue statement of a
material fact or omit to state a material fact necessary to make the statements
made, in light of the circumstances under which such statements were made, not
misleading with respect to the period covered by this report;
3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations, changes in net assets, and cash
flows (if the financial statements are required to include a statement of cash
flows) of the registrant as of, and for, the periods presented in this report;
4. The registrant's other certifying officers and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Rule 30a-3(c) under the Investment Company Act of 1940) for the registrant and
have:
a) designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those
entities, particularly during the period in which this report is being
prepared;
b) evaluated the effectiveness of the registrant's disclosure controls and
procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures, as of a date
within 90 days prior to the filing date of this report based on such
evaluation; and
c) disclosed in this report any change in the registrant's internal control
over financial reporting that occurred during the registrant's most recent
fiscal half-year (the registrant's second fiscal half-year in the case of
an annual report) that has materially affected, or is reasonably likely to
materially affect, the registrant's internal control over financial
reporting; and
5. The registrant's other certifying officers and I have disclosed to the
registrant's auditors and the audit committee of the registrant's board of
directors (or persons performing the equivalent functions):
a) all significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are reasonably
likely to
<Page>
adversely affect the registrant's ability to record, process, summarize,
and report financial information; and
b) any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrant's internal control
over financial reporting.
Date: September 30, 2003
/s/ Thomas S. Schreier, Jr.
- ---------------------------
Thomas S. Schreier, Jr.
President
*************************
I, Robert H. Nelson, certify that:
1. I have reviewed this report on Form N-CSR of American Municipal Income
Portfolio Inc.;
2. Based on my knowledge, this report does not contain any untrue statement of a
material fact or omit to state a material fact necessary to make the statements
made, in light of the circumstances under which such statements were made, not
misleading with respect to the period covered by this report;
3. Based on my knowledge, the financial statements, and other financial
information included in this report, fairly present in all material respects the
financial condition, results of operations, changes in net assets, and cash
flows (if the financial statements are required to include a statement of cash
flows) of the registrant as of, and for, the periods presented in this report;
4. The registrant's other certifying officers and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Rule 30a-3(c) under the Investment Company Act of 1940) for the registrant and
have:
a) designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our supervision, to
ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those
entities, particularly during the period in which this report is being
prepared;
b) evaluated the effectiveness of the registrant's disclosure controls and
procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures, as of a date
within 90 days prior to the filing date of this report based on such
evaluation; and
c) disclosed in this report any change in the registrant's internal control
over financial reporting that occurred during the registrant's most recent
fiscal half-year (the registrant's second fiscal half-year in the case of
an annual report)
<Page>
that has materially affected, or is reasonably likely to materially affect,
the registrant's internal control over financial reporting; and
5. The registrant's other certifying officers and I have disclosed to the
registrant's auditors and the audit committee of the registrant's board of
directors (or persons performing the equivalent functions):
a) all significant deficiencies and material weaknesses in the design or
operation of internal control over financial reporting which are reasonably
likely to adversely affect the registrant's ability to record, process,
summarize, and report financial information; and
b) any fraud, whether or not material, that involves management or other
employees who have a significant role in the registrant's internal control
over financial reporting.
Date: September 30, 2003
/s/ Robert H. Nelson
- ----------------------
Robert H. Nelson
Treasurer