The sudden illness of South Dakota Sen. Tim Johnson sent Washington politicians and reporters scurrying to the rule books for answers:
What happens when a member of Congress becomes incapacitated?
It turns out there are different answers for members of the House and Senate. And different answers, too, depending on the particular state.
What is legal in your state may be illegal in the state next door.
When the House has a vacancy, the Constitution says it must be filled by a special election. But the Constitution permits Senate vacancies to be filled either by special elections or by appointments from governors.
According to the Congressional Research Service at the Library of Congress, it is up to state legislatures to grant that power to governors. And some states have refused to do that.
Alaska, Oregon and Wisconsin expressly forbid the governor to make an interim appointment. Those three states require special elections. Oklahoma's statute requires close reading, and even then it can sound confusing.
The CRS says, "If the vacancy occurs after March 1 of any even-numbered year and the term expires the following year, no special election is held; rather, the governor is required to appoint the candidate elected in the regular general election to fill the unexpired term." Well, as we said, it requires close reading.
Democrats are nervous because Johnson, a Democrat, comes from South Dakota, one of the states that permit the governor to choose a replacement from a different party than the senator who is replaced.
The governor of South Dakota, Mike Rounds, is a Republican. He could legally choose a Republican to serve the remainder of Johnson's term through 2008. That would give the GOP control of the closely divided Senate.
Democrats would be a lot less nervous if Johnson came from a state that severely restricts the governor's authority. Arizona and Hawaii require the governor to choose a replacement from the previous incumbent's party. In Utah and Wyoming, the governor has to choose from among three people proposed by the previous incumbent's party.
Choosing someone from the previous incumbent's party does not guarantee that a governor will avoid controversy.
Many Alaskans were angry in December 2002, when Gov. Frank Murkowski appointed a fellow Republican to the Senate seat he resigned when he was elected governor. But that fellow Republican was his daughter, Lisa.
Opponents charged nepotism. Alaskans decided to change how vacancies would be filled. They voted to take this power away from governors. Special elections are now required to fill Senate vacancies. Lisa Murkowski managed to survive politically, and won the 2004 election. But her father lost his bid for re-election in the GOP primary last August.
No one knows whether Johnson will able to perform his duties following brain surgery.
As ABC's Jake Tapper notes in his blog, the Constitution does not give anyone the authority to say when a senator is incapacitated. And some senators have remained in office for long periods, despite severe illness and diminished mental capacity. So did President Woodrow Wilson, whose wife, according to historians, often made decisions for him after he suffered a severe stroke 18 months before his term expired.
For now, politicians in Washington and South Dakota have avoided any public remarks on the possible political impact of Johnson's condition. Rounds has urged the people of his state to pray for the senator's recovery.