Matheson objected to language in the bill that he said would "compromise the safety of our troops on the ground." He has said previously he would not support any bill containing a date-certain withdrawal, and he took issue with how the debate came down to Republican vs. Democrat.
"I am saddened that this important issue devolved into a partisan debate," Matheson said in a statement. "It's immoral to play politics with the needs of the men and women who protect the ideals we hold so dear."
Matheson had proposed an amendment to allow President Bush to decide the withdrawal date and for him to ensure the date was "classified." The amendment, though, didn't get included into the debate.
If Matheson's version were to become law, I can let you in on a little secret. Bush's classified withdrawal date would be the same his public date: "not on my watch." Bush doesn't want the fall of Saigon images to happen while he is still in the White House. He dreams that this alone will save his legacy. But people don't blame Ford for ending the Vietnam war, they blame LBJ for starting it for real, and Nixon for bombing Cambodia illegally, and then suing for peace. Or they blame the liberals in Congress in the 1970s for defunding the war. But not Ford.
And Bush's presidency has been done since he got reelected. That was his only real accomplishment.