Castle will not back O'Donnell

A Rep. Mike Castle (R-Del.) campaign source confirmed to The Hill late Tuesday that the longtime congressman will not be endorsing Christine O'Donnell.

The Tea Party-backed O'Donnell defeated Castle for Delaware's Republican Senate nomination.

After the stunning primary loss, Castle's campaign also said the longtime congressman is not interested in waging a write in bid this November.

In Alaska, Sen Lisa Murkowski (R-Alaska) is contemplating an independent write in campaign after she lost to Tea Party backed Joe Miller in the August GOP primary.

As to whether the national party would back O'Donnell, a Castle campaign source said the campaign has no knowledge of their thinking but said "they should save their money."