Fox News Washington bureau managing editor Brit Hume, CBS national political correspondent Gloria Borger, and Fox News host Neil Cavuto reported that if Sen. Tim Johnson (D-SD), who was hospitalized on December 13 with intracerebral bleeding and underwent brain surgery, were “incapacitated” or “unable to serve in any way,” or his condition were to “worsen,” then South Dakota Gov. Michael Rounds (R) would appoint a replacement to take Johnson's seat until the 2008 general election. In fact, the U.S. Constitution states that the governor may appoint a replacement senator only if Johnson's seat becomes vacant and, in contrast with provisions concerning the presidency, includes no provision allowing officials to declare that a senator is incapable of serving. Indeed, several senators have remained in office despite significant infirmities.

The 17th Amendment to the U.S. Constitution states: “When vacancies happen in the representation of any State in the Senate, the executive authority of such State shall issue writs of election to fill such vacancies: Provided, That the legislature of any State may empower the executive thereof to make temporary appointments until the people fill the vacancies by election as the legislature may direct.” The Constitution does not address the ability of a Senator to carry out his or her duties. In contrast, the 25th Amendment deals specifically with “Presidential Disability” and provides a mechanism for people other than the president to determine that the president is “unable to discharge the powers and duties of his office” and appoint a replacement without the president's permission.

South Dakota state law echoes the 17th Amendment: “Pursuant to the Seventeenth Amendment to the Constitution of the United States of America, the Governor may fill by temporary appointment, until a special election is held pursuant to this chapter, vacancies in the office of senator in the Senate of the United States.”

As USA Today reported on December 14, there exists no legal precedent for declaring a senator unable to serve, and senators have continued to serve in spite of infirmities:

Political scientist David Brady of Stanford University's Hoover Institution said history is filled with examples of lawmakers remaining in office no matter how severe their disabilities. Brady recalled Sen. Clair Engle of California [D], unable to speak because of a brain tumor, casting an “aye” vote for the 1964 Civil Rights Act by pointing to his eye.

More recently, 100-year-old Strom Thurmond [R] completed his last term as a South Carolina senator while living at Walter Reed Army Hospital.

There is no legal provision for declaring a member of Congress too infirm to serve, Brady said.

“The Constitution also does not provide an effective way for filling temporary vacancies that occur when members are incapacitated,” said a May 2003 report by a government panel convened to determine how Congress would continue in the wake of a terrorist attack.

MSNBC.com offered other “examples of a senator being incapacitated for years and remaining in office”:

Most recently, Sen. Karl Mundt [R] (coincidentally, also from South Dakota) suffered a stroke in 1969 and was incapacitated, but he refused to step down. He remained in office until January 1973, when his term expired. Mundt was pressured repeatedly to step down during his illness, but he demanded that the governor promise to appoint his wife. The governor refused, and Mundt remained in office.

Another example was Sen. Carter Glass, D-Va. Glass had a heart condition that prevented him from working for most of his last term after his re-election in 1942. Yet Glass refused to resign, and finally died of congestive heart failure in May 1946, in his apartment at the Mayflower Hotel in Washington.

From the December 13 edition of Fox News' Special Report with Brit Hume:

HUME: South Dakota's two-term Democratic Senator Tim Johnson is hospitalized tonight after falling ill in his Washington office. Doctors at George Washington University Hospital are evaluating Johnson, who is 59, for signs he may have suffered a stroke. If Johnson's condition were to worsen and he were incapacitated, South Dakota's Republican governor, Republican governor, would name a replacement to serve until the next general election, potentially creating a tie between Senate Democrats and Republicans and giving the tie-breaking vote, once again, to Vice President [Dick] Cheney.

From the December 13 broadcast of the CBS Evening News with Katie Couric:

BORGER: Well, Katie, first of all, tonight everyone in Washington is hoping for the best for Senator Johnson, but they also understand that his condition could really determine control of the Senate. Right now, the Senate is controlled by the Democrats by one seat. If Senator Johnson is unable to serve in any way, then the Republican governor of the state of South Dakota would have to appoint a replacement for him. He would likely appoint a Republican, and, Katie, that would send control of the Senate back to the Republican Party. It would be 50/50. Dick Cheney, the vice president, would be the deciding vote, and the committee chairmen would all be Republicans again, and that would control the congressional agenda.

From the December 13 edition of Fox News' Your World with Neil Cavuto:

CAVUTO: All right, just before the new Senate is to take hold, one of its key members has apparently had a stroke. That's the indications we're getting from the Associated Press, that Senator Tim Johnson, a Democrat of South Dakota, was taken to George Washington University Hospital suffering from a possible stroke. That is all we know. You know as close as the Senate -- the new Senate is, with 49 Democrats, 49 Republicans, and two independents who ostensibly will be voting along the Democratic side, that this is close as a tick. And anything, anything, that hints that that could possibly be changed -- well, the health condition of any one of those 100 members gets overly scrutinized, perhaps here as well. Again, keep in mind as well that the governor of South Dakota is a Republican, Michael Rounds. And should the senator's condition worsen, it would be up to the governor to find a replacement.