In the case of Tom Daschle, it may just be political expediency, as Tom is considering a presidential run and the most recent polls show that the majority of Americans favor the NSA wire tapping.
David Limbaugh has some things to say on this in his column.
"They went on to mislabel the NSA intercepts where at least one party was not located in the United States as "domestic spying." Both words, "domestic," and "spying," were calculated to paint the president in a negative light and to taint what these Democrats now acknowledge is a program that is "necessary for fighting terrorism."
The "domestic" label was clearly misleading in that it implied that all parties to the communication were located on American soil, which is not the case. By coupling it with "spying," they intended to conjure up images of Dan Aykroyd impersonating a paranoid Richard Nixon mulling his enemies list in the Oval Office, then equating George Bush with this ugly practice.
It fit nicely with their long-running scheme to depict the president as the autocratic "King George," who acts unilaterally, beyond his constitutional authority and in derogation of the people's rights, to spy on innocent American citizens. This has always been a pernicious lie. The NSA surveillance program specifically excluded purely domestic communications and was never targeted at innocent citizens but at conversations where at least one party was a known or suspected terrorist."