Sen. Tim , D-S.D., was reported to be in critical condition early today after undergoing emergency surgery, placing Democratic control of the U.S. Senate next year into question.

His grave illness raises anew questions as to which party will have the upper hand as Congress deals with such critical industry issues as extension of the Terrorism Risk Insurance Act after 2007, the optional federal charter, and removal of the ban on government-established rates for the prescription drug benefit program under Medicare.

Sen. Christopher Dodd, D-Conn., chairman-designate of the Senate Banking Committee, has already indicated he would support making TRIA permanent.

Democrats in general have promised to get the government more involved in the operation of the prescription drug program under Medicare, which has effectively been delegated by the Bush administration to health insurers.

underwent emergency brain surgery overnight after falling ill at the Capitol and was in critical condition early this morning, according to The Washington Post.

Johnson’s illness brings into question control of the Senate in the next Congress because Democrats have only a 1-vote majority in the Senate. If Johnson is incapacitated or otherwise unable to serve, a successor would be chosen by the Republican governor of South Dakota, insurance agent Michael Rounds.

That would create a 50-50 tie, potentially giving Vice President Dick Cheney the authority to keep Republicans in control of the Senate.

Johnson, 59, was taken to George Washington University Hospital at noon yesterday afternoon, shortly after becoming disoriented during a conference call with news reporters. He underwent “a comprehensive evaluation by the stroke team,” his office said. Aides later said he had not suffered a stroke or heart attack.

Nursing supervisor Quinn Collins told The Washington Post early today that the senator was out of surgery and in critical condition. Hospital officials and Johnson aides offered no further comment or details; a more complete statement was expected later this morning.

Johnson was co-author of a bill introduced in the last Congress that would create an optional federal charter for insurers, and he has indicated to the industry that he would reintroduce such legislation in the new 110th Congress.

Rounds, however, while publicly stating that he is not a candidate, is being pushed by the Independent Insurance Agents and Brokers of America, Washington, amongst others, to challenge Johnson for re-election in 2008, presumably because he would not support an OFC, which the IIABA opposes.

Rounds also opposed efforts by the Council of Insurance Agents and Brokers, Washington, to break countersignature laws, testifying in federal court against the CIAB legal initiative last year. The state’s countersignature law was later ruled by a judge to be unconstitutional.

Johnson was expected to head the Senate Banking Committee’s key Financial Institutions Subcommittee, succeeding Robert Bennett, R-Utah. This is the banking panel committee that deals with all regulatory, accounting and legal issues involving financial institutions.

Johnson’s inability to serve or resignation could result in Sen. Richard Shelby, R-Ala., who opposes an extension of TRIA, remaining in control of the panel.

In a commentary written late Wednesday on the implications of a 50-50 tie, Joe Lieber of Washington Analysis writes that the effects of a tie could affect the structure of Senate committees in ways that would make moving legislation more difficult.

In 2001, the last time there was a tie in the Senate, Sen. Trent Lott, R-Miss., was named majority leader and Republicans had nominal control because of Cheney’s authority to break ties in the Senate, Lieber writes.

Republicans maintained their status as chairmen of the committees; an equal number of Republicans and Democrats were represented on all committees; and committee budgets for both the majority and minority were equally divided, Lieber writes.

Also, the agreement gave power to the majority or minority leader to discharge legislation or nominations that had not been reported out of committee because of tie votes, and motions to cut off debate on any amendable item were prohibited during the first 12 hours of consideration. The restrictions made it easier to filibuster legislation or simply to eat up time, Lieber says.

“If a 50-50 tie occurs, the parameters for organizing the Senate this time around could be different, but we suspect they will fall along these lines,” Lieber writes.