Who can pay the expenses of the 14 Wisconsin Senate Democrats who left the state?

Partial answer: campaign contributors.

"The Government Accountability Board staff has been asked whether campaign funds may properly be used by the 14 Democrat senators currently absenting themselves from the state to pay for hotels and other expenses incurred as a result of the decision to leave," wrote Board general counsel Kevin Kennedy in a February 22 letter to state senators.  "In the opinion of the Board's staff, campaign funds may be used for this purpose."

The Washington Examiner has more here.