The Big Ten is expected to move ahead with formal offer letters for Oregon and Washington, sources told ESPN's Pete Thamel on Friday.

Sources said a vote by the conference -- which is expected to be unanimous -- would take place Friday to formalize the two schools' admission, barring any last-minute snags.

Big Ten presidents and chancellors met early Thursday morning and authorized commissioner Tony Petitti to explore adding Oregon and Washington, which would follow USC and UCLA in making the jump from the Pac-12.

The Big Ten had explored adding Oregon and Washington in the months following the addition of USC and UCLA, sources told ESPN, but that quest ended in part because of complications in funding the schools at a full share. Sources told ESPN on Thursday that Oregon and Washington would be given only a partial share as new members.