The death of a U.S. Senate incumbent up for re-election this year may affect other Senate races around the country.

The tragic death of Minnesota Sen. Paul Wellstone, along with his wife and daughter, campaign aides and two pilots, in a plane crash early Friday adds another unique and intriguing aspect to this year’s national campaign.

About a year ago, Missouri Gov. Mel Carnahan, who was running for the U.S. Senate, was killed in a similar place crash just days before the election. That crash also took place in poor weather conditions. His wife was a last-minute fill-in on the Democratic Senate ticket and won a close election over the incumbent Sen. John Ashcroft.

This year’s Missouri contest has been projected as a tight race, and there is a question of whether the loss of Wellstone in a similar accident will cause some Missouri voters to shift their support to Mrs. Carnahan.

Who will replace Wellstone as the Democratic candidate in Minnesota? Is there any chance retiring Gov. Jesse Ventura will join the race against Republican Norman Coleman? Ventura has the name recognition and he still enjoys high popularity in Minnesota. He is an Independent, but many Democrats and Republicans might vote for him as well as is fellow Independents.

The Senate race in New Jersey is a joke, with Democratic Sen. Robert Torricelli dropping out when various polls showed he was sure to lose to his GOP challenger. Although New Jersey laws prohibits a replacement on the ballot if a candidate drops out within 51 days before the election, Democrats brought in former New Jersey Sen. Frank Lautenberg to replace Torricelli. The state Supreme Court agreed, even thought it was counter to state law, and Democrats are likely to pull a win out of what appeared to be a sure loss.

The balance of power in the Senate could not be more tenuous  one vote! Democrats control the Senate by a single vote, so every Senate race is critical to both the GOP and the Democrats.

What effect will Wellstone’s death have on races in Missouri and Minnesota and all other Senate contests? Will Democrats in all states with a Senate race think it is even more important for them to vote? Or will Republicans think they need to get out and vote to have a chance to take control of the Senate.

At this stage, it’s anyone’s guess, and it makes exciting Senate races even more intriguing.