<PAGE>
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                  SCHEDULE TO
            TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                                 CNA SURETY CORP
                       (Name of subject company (issuer))

                     CONTINENTAL CASUALTY COMPANY (OFFEROR)
                      (Names of filing persons (identifying
                  status as offeror, issuer or other person))


                          Common Stock, $.01 par value
                         (Title of Class of Securities)

                                   12612L1008
                      (CUSIP Number of Class of Securities)

                            Jonathan D. Kantor, Esq.
               Senior Vice President, General Counsel & Secretary
                                   CNA Plaza
                            Chicago, Illinois 60685
                                 (312) 822-1384
   (Name, address and telephone number of person authorized to receive notices
                 and communications on behalf of filing persons)


                           CALCULATION OF FILING FEE
|--------------------------------------------|-------------------------------|
|TRANSACTION VALUATION*                      |     AMOUNT OF FILING FEE      |
|--------------------------------------------|-------------------------------|
|Filing  relates solely to preliminary       |            None               |
|communications  made before the commencement|                               |
|of a  tender offer                          |                               |
|--------------------------------------------|-------------------------------|
*Set forth the amount on which the filing fee is calculated and state how it was
determined.

[ ]  Check  the  box if any  part  of the  fee is  offset  as  provided  by Rule
0-11(a)(2)  and identify the filing with which the offsetting fee was previously
paid. Identify the previous filing by registration statement number, or the Form
or Schedule and the date of its filing.

Amount Previously Paid: _____________

Form or Registration No.: _____________

Filing Party: ________________________

Date Filed:  _________________________
<PAGE>
[X] Check the box if the filing  relates  solely to  preliminary  communications
made before the commencement of a tender offer.

Check the  appropriate  boxes below to designate any  transactions  to which the
statement relates:

[X] third-party tender offer subject to Rule 14d-1.

[   ] issuer tender offer subject to Rule 13e-4.

[X] going-private transaction subject to Rule 13e-3.

[  ]  amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer: [ ]


 CNA                    MEDIA:
                                     CNA Plaza              Clark Walter
                                     Chicago, IL  60685     312-822-1454

                                                             ANALYSTS:
                                                             Donald P. Lofe, Jr.
                                                             312-822-3993
CNA
FOR ALL THE COMMITMENTS YOU MAKE


NEWS

                    CNA ANNOUNCES PROPOSED CASH TENDER OFFER
                          FOR ALL SHARES OF CNA SURETY

CHICAGO,  IL., March 20, 2000 - CNA Financial  Corporation (NYSE: CNA) announced
today that Continental  Casualty Company (CCC), a wholly owned  subsidiary,  has
proposed to CNA Surety Corporation (NYSE: SUR) that CCC make a cash tender offer
at $13.00 per share for all shares of CNA Surety  common stock not already owned
by CCC and its affiliates. This move is consistent with CNA's recently announced
intention to sharpen its strategic focus on serving  businesses.  The $13.00 per
share price  represents a 17.4% premium over CNA Surety's  average closing price
for the past 30 trading days of $11.07 per share.

CCC and its affiliates currently own approximately 62 percent of the outstanding
shares of CNA Surety  common  stock.  CCC intends to condition  the tender offer
upon receiving enough shares so that its ownership  reaches at least 90 percent.
If this  ownership  threshold is achieved,  CCC would then acquire the remaining
outstanding  shares of CNA Surety  common  stock not  tendered  to CCC through a
statutory  "short-form"  merger  process.  Stockholders  who do not tender their
shares to CCC during the tender  offer  would also  receive  $13.00 per share in
cash for their stock in the short-form merger.

CCC  intends to  negotiate  a  definitive  agreement  with CNA  Surety  prior to
commencing the offer.

CNA Financial  Corporation is a holding company whose primary  subsidiaries  are
property-casualty and life insurance companies. Collectively, these subsidiaries
are CNA, one of the largest insurance organizations in the United States.

                                     -more-
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OTHER IMPORTANT INFORMATION:

The tender offer described in this  announcement  for the outstanding  shares of
CNA Surety  common  stock has not yet  commenced.  As soon as the  tender  offer
commences,  we will  file a  tender  offer  statement  with the  Securities  and
Exchange Commission.  You should read the tender offer statement when it becomes
available because it will contain important  information about the tender offer.
You can obtain the tender offer  statement  and other  documents  that are filed
with the  Securities  and Exchange  Commission  for free on the  Securities  and
Exchange  Commission's web site at  http://www.sec.gov.  If you write us or call
us, we will send you the following documents for free when they are available:

tender offer statement (except for exhibits)
offer to purchase
letter of transmittal
notice of guaranteed delivery

You can call us at (312) 822-6312 or write to us at:

         CNA Financial Corporation
         c/o Corporate Secretary
         333 South Wabash
         Chicago, IL 60690

                           FORWARD LOOKING STATEMENT

The following constitutes a "Safe Harbor" statement under the Private Securities
Litigation  Reform Act of 1995:  This  press  release  contains  forward-looking
statements that involve a number of risks and  uncertainties.  Important factors
that could cause actual  results to differ  materially  from those  indicated by
such forward-looking statements are set forth under the heading "Forward-Looking
Statements"  included in the  Management's  Discussion  and Analysis of Reported
Operations and Liquidity set forth in CNA Financial  Corporation's Annual Report
to Stockholders for the year ended December 31, 1998,  incorporated by reference
in Item 7 of that  Corporation's  Annual  Report on Form 10-K for the year ended
December  31,  1998.  These  include  risks and  uncertainties  relating to, for
example,  a material adverse change to CNA Surety's  business or prospects,  the
effect of economic conditions, and rating agency policies and practices.

                                      ###

Further Information:

You can call Donald P. Lofe Jr.@ 312-822-3993 or write to us at:

         Investor Relations Department
         Continental Casualty Company
         333 South Wabash
         Chicago, IL  60690