Ambac Financial

(ABK)

and other bond insurers are working on a plan to send to the

Treasury Department

that would enable them to sell troubled assets to the government,

Bloomberg

reports.

The companies also may present a proposal next week that would allow the insurers to guarantee some assets with government backing, CEO Michael Callen said in a

Bloomberg

interview.

``We're working hard to put together a proposal and it's got to be an industry proposal,'' Callen said,

Bloomberg

reports. ``We don't have a lot of time.''

Callen said he isn't asking Treasury to take a stake in Ambac.

The U.S. Treasury said Thursday it isn't considering buying equity holdings in bond insurers,

Bloomberg

reports.

Five of seven bond insurers, including

MBIA

(MBI) - Get Report

and Ambac, lost their top AAA ratings this year as losses surged on securities linked to subprime mortgages, reports

Bloomberg

.

This article was written by a staff member of TheStreet.com.