T. LOUIS - In the flash of a fireball, an airplane crash killed Missouri's governor, cast a pall over this year's final presidential debate, and freshened doubts about Democratic hopes of reclaiming the US Senate.
Governor Mel Carnahan, 66, his son Roger, and a political aide, Chris Sifford, died Monday night when their six-seat Cessna plunged amid a thunderstorm into hilly, wooded terrain about 25 miles south of St. Louis. The three, with Roger ''Randy'' Carnahan at the controls, had been headed from the city to a fund-raiser in New Madrid.
The impact was felt all the way in Washington, where Carnahan was viewed as one of the Democrats' strongest hopes for gaining a US Senate seat in next month's elections.
The two-term governor, who under a term-limits law could not seek reelection, was running even with Senator John Ashcroft, the Republican incumbent. A Zogby poll taken for the St. Louis Post-Dispatch the first week of September gave Ashcroft 45 percent and Carnahan 43 percent, within the 4-percentage point margin of error.
The GOP controls the Senate 54-46, with 34 seats up for election. Thirteen seats are considered up for grabs, with Republicans controlling eight and Democrats five. Democratic prospects for gaining a majority were seen as a longshot, but Carnahan's death was a blow to the party psyche.
''Carnahan was one of the best Senate candidates in the country,'' said a top Democratic political strategist in the Senate. ''They had run a two-year campaign, he had two terms as the governor, and they were running a flawless race.''
One political analyst, Dale Neuman of the University of Missouri-Kansas City, speculated Carnahan's death could diminish turnout for Vice President Al Gore in his own neck-and-neck race against Republican presidential contender George W. Bush.
''Mel was always a ticket leader, pulling everybody else along with him,'' Neuman said.
The crash occurred as Bush and Gore were in Missouri preparing for last night's debate at Washington University in suburban Clayton. Bush's arrival in St. Louis on Monday night was delayed for about a half-hour because of thunderstorms.
Frank J. Fahrenkopf Jr., co-chairman of the Commission on Presidential Debates, said organizers considered postponing the debate, but decided to forge ahead because of the importance of the presidential election and the belief that Carnahan would have preferred it.
''It was a tragedy, but this is a national and, in many ways, international event, and had to proceed,'' Fahrenkopf said. ''We're down to the last three weeks of this campaign, and it would be a major disruption not to do it.''
Debate moderator Jim Lehrer started the proceedings with a statement about Carnahan and a moment of silence. Gore and his wife, Tipper, visited Carnahan's campaign headquarters yesterday afternoon. He called the crash a ''shocking and devastating tragedy'' and was expected to visit Carnahan's widow, Jean, today. The couple had three other grown children.
The vice president also canceled a postdebate rally and replaced a planned visit to Kansas City today with a stop in Iowa. Bush also canceled his postdebate rally.
''Mel was a thoughtful, distinguished man who was dedicated to quality education and excellence in public service,'' Bush said in a statement.
Massachusetts Governor Paul Cellucci, who traveled yesterday to St. Louis, recalled that Carnahan had hosted other governors two summers ago at a National Governors' Association meeting. ''He was a very gracious host,'' Cellucci said. ''It was pretty clear he was a very well-liked and popular governor in Missouri. So this is certainly a tragic loss for that state.''
For many, Carnahan's crash stirred memories of a similar episode in 1976.
US Representative Jerry Litton, a Democrat, was killed along with his wife and two children as they flew to Kansas City for a victory celebration after he won the US Senate primary. His would-be Republican rival, John Danforth, went on to a distinguished career in the Senate.
Like many states, Missouri is so large that candidates often travel by plane to save time. Many such campaign events take place late at night, and it is a rare campaign that doesn't have a story of at least one hair-raising flight.
Roger Carnahan, a lawyer known locally as Randy, along with his father and Sifford, took off from St. Louis Parks Airport in a twin-engine Cessna 335 at 6:55 p.m. CDT. They were following an instrument flight plan when they encountered bad weather.
Carol Cardmody, a member of the National Transportation Safety Board, said the last radar contact with the plane was at 7:33 p.m., and the first 911 call was received at 7:36 p.m.
A local television station said the last radio communication with the plane was when it reported thunderstorms and asked to climb to 7,000 feet. The Associated Press reported that Sifford called a state Democratic official from the plane to say they had run into lightning and were returning to St. Louis or Jefferson City, the state capital.
Ashcroft's campaign immediately suspended all operations. ''Obviously this is not a time for politics. This is a time for the state to come together,'' the senator said.
Under Missouri law, Carnahan's name will stay on the Nov. 7 ballot, since the deadline for changing it passed last Friday. That left the possibility of the Democrats winning a sympathy vote.
Should Carnahan get more votes than Ashcroft, Lieutenant Governor Roger Wilson would name a successor until the next general election in 2002. Wilson, a Democrat serving as acting governor until Carnahan's death is confirmed, has that authority because the Senate is being sworn in Jan. 3, five days before Missouri's new governor takes office.
Tina Cassidy of the Globe Staff contributed from Boston to this report.
