Proof of DeLay violating House rules?

The Washington Post claims to have proof that DeLay charged his Scotland golf trip to a credit card owned by lobbyist Jack Abramoff:

"The airfare to London and Scotland in 2000 for then-House Majority Whip Tom DeLay (R-Tex.) was charged to an American Express card issued to Jack Abramoff, a Washington lobbyist at the center of a federal criminal and tax probe, according to two sources who know Abramoff's credit card account number and to a copy of a travel invoice displaying that number.

DeLay's expenses during the same trip for food, phone calls and other items at a golf course hotel in Scotland were billed to a different credit card also used on the trip by a second registered Washington lobbyist, Edwin A. Buckham, according to receipts documenting that portion of the trip.

House ethics rules bar lawmakers from accepting travel and related expenses from registered lobbyists. DeLay, who is now House majority leader, has said that his expenses on this trip were paid by a nonprofit organization and that the financial arrangements for it were proper. He has also said he had no way of knowing that any lobbyist might have financially supported the trip, either directly or through reimbursements to the nonprofit organization.

The documents obtained by The Washington Post, including receipts for his hotel stays in Scotland and London and billings for his golfing during the trip at the famed St. Andrews course in Scotland, substantiate for the first time that some of DeLay's expenses on the trip were billed to charge cards used by the two lobbyists. The invoice for DeLay's plane fare lists the name of what was then Abramoff's lobbying firm, Preston Gates & Ellis."