Wyman said her office - which oversees elections - and the county offices that administer elections were not made aware that the postcard would be sent to Washington voters.
If voters will not be able to access their mail during the 18-day voting period, need to receive their ballot at a different address, or need to access their ballot electronically, they should contact their County Elections Office.
The pre-election mailers, meant to inform Americans about voting by mail, advise voters to request a vote-by-mail ballot at least 15 days before Election Day and to return the official ballot at least seven days before.
In a statement, the USPS did not directly address the potentially misleading statements on its informational circulars for California voters. If they are registered to vote, one will automatically be sent to them. "It can undermine confidence in the election & suppress votes".
"As the Chief Election Official of the state of Colorado, it's my job to try to stop misinformation and any unnecessary election confusion", she added.
Griswold said she asked the Postal Service not to mail the postcard with misinformation, but it refused.
She contended that a failure to listen to local experts combined with the recent postal delays in some parts of the country is "beyond suspect".
Griswold said in a statement that she first learned just two days ago that the postcards would be sent to households across the USA, and voters have already begun receiving them in the mail.
Those changes have come as President Donald Trump has repeatedly disparaged the concept of mail balloting - a longtime practice in Washington and other states - as he trails in general election polls.
Secretary of State Jena Griswold filed suit against several USPS executives on Saturday, including Postmaster General Louis DeJoy, alleging that the USPS "intends to mail an official notice to all Colorado voters that provides false statements about voting in Colorado", which could have the effect of disenfranchising voters.
The postcard, which Griswold posted on social media, provides a checklist for preparing to vote by mail.
"We appreciate that somebody at the U.S. Postal Service was trying to help", Dalton said, "but unfortunately the message, in being generic for an entire nation, doesn't really work".