John McCain v. Bush

If the McCain amendment prevails in the Senate-House conference, the White House has threatened that George W. Bush will veto the $440 billion Defense Appropriations bill, $50 billion of which is for continuing war in Iraq and for the troubles in Afghanistan.
Last summer, at the order of the president, this—and two other corollary McCain amendments to the same appropriations bill—resulted in Senate Majority Leader Bill Frist yanking the entire $440 billion appropriations bill off the Senate floor. The White House was afraid the McCain amendments setting clear standards of prisoner treatment would pass.
Before that happened, Dick Cheney had been sent to muscle McCain to withdraw his amendments. McCain refused. More White House pressure was put on McCain and some of his co-sponsors at the beginning of October, when the appropriations bill came up again. Having refused to crack under North Vietnamese torturers, McCain was not moved.