With control of the Senate up in the air, Thursday found the AP struggling to get a grip on constitutional fine points. The wire service reported at midday that “the possibility of another evenly divided chamber hovered over the Capitol” as Democratic Senator Tim Johnson of South Dakota “recovered from brain surgery. If Johnson is unable to serve, South Dakota Gov. Michael Rounds, a Republican, would appoint someone to fill his vacated seat. A Republican appointment would split the Senate anew, giving Vice President Dick Cheney the tie-breaking role and handing control of the chamber to Republicans.”

But another AP story said something slightly different, and it’s a difference that makes all the difference: “If Johnson leaves the Senate, the Republican governor of South Dakota could appoint a Republican to fill the remaining two years of Johnson’s term.” This story went on to explain, “Senate historian Don Ritchie said senators serve out their terms unless they resign or die. Nine senators have remained in the Senate even though illnesses kept them away from the chamber for six months or more.”

So Johnson could sit even if he couldn’t serve. If he didn’t show up when the Senate was organized, the Democrats would command a 50-49 majority.