When I attempt to authorise access to my Blogger blog, I log in via Google Accounts and am redirected to a page displaying:
The page you have requested cannot be displayed. Another site was requesting access to your Google Account, but sent a malformed request. Please contact the site that you were trying to use when you received this message to inform them of the error. A detailed error message follows:
The site "[ROOT LEVEL DOMAIN]" has not been registered.
Perhaps allow the upload of a Blogger XML file instead? Exporting a Blogger blog to an XML file is an easy process.