Sen. Paul Wellstone, D-Minn., died in a plane crash Friday along with seven others.

"It does not look like there are survivors. It is the unthinkable," said campaign manager Jeff Blodgett.

On board with the 58-year-old senator were his wife Sheila, his daughter Marcia, three campaign workers and two pilots, transportation officials told Fox News.

"Our prayers and heartfelt sympathy goes to their sons, their loved ones, their friends and the people of Minnesota. Paul Wellstone was a man of deep convictions. He was a plainspoken fellow who did his best for his state and for his country. May the good Lord bless those who grieve," President Bush said Friday.

Bush had been scheduled to go to Minnesota Monday to campaign for Wellstone's opponent, former St. Paul Mayor Norm Coleman. That trip has been canceled.

The race between Coleman and Wellstone was watched across the nation as one of the contests that could determine the majority party in the Senate.

Coleman suspended his campaign after hearing of the crash.

"The people of Minnesota have experienced a terrible, unimaginable tragedy," Coleman said.

"Paul Wellstone was the soul of the Senate. He was one of the most notable and courageous men I have ever known. He was a gallant and passionate fighter, especially for the less fortunate. I am grateful to have known Paul and Sheila as dear and close friends," said Senate Majority Leader Tom Daschle, D-S.D.

"All Minnesotans and all Americans today are saddened by this tragedy. One of the most powerful voices for justice in this country has been silenced," said Minnesota's junior Sen. Mark Dayton.

Wellstone, considered the most liberal senator in Congress, was headed from St. Paul to Eveleth-Virginia Municipal Airport northwest of Duluth in a chartered twin engine King Air A-100 turboprop, said to be one of the safest planes in the air.

The family was scheduled to attend the funeral of Martin Rukavina, father of Minnesota state Sen. Tom Rukavina.

The plane lost radio contact with the tower at 10:21 a.m. local time and crashed two miles from the runway, according to National Transportation Safety Board officials.

The plane's pilots called the airport to get clearance for landing when they were about seven miles out, and they reported no problems, said Gary Ulman, who was on duty at the small airport at the time.

When the plane didn't land, Ulman said he took off in another plane to search for it. About two miles southeast of the airport, he saw smoke.

"The wreckage was scattered and fully engulfed in flames. Just looking at it, it would take a miracle to survive it," he said.

Officials said the plane made an instrument approach, rather than a visual, line of sight approach. That means it was being guided by air traffic control and instruments were used on the plane to assist in the landing.

Freezing drizzle and light snow had been falling and there was light fog, but officials are not certain the weather contributed to the crash.

The National Transportation Safety Board sent a nine-member team to determine the cause of the accident.

At the site, FBI spokesman Paul McCabe said there was no indication the crash was related to terrorism. He also said it may take time to recover the bodies.

The King Air turboprop was made by Raytheon Corp. with Pratt & Whitney engines, according to the Federal Aviation Administration. The owner was listed as Beech Transportation Inc. of Eden Prairie, Minn., and the plane had been leased by Wellstone.

There were early reports that Sen. Ted Kennedy, D-Mass., might have been on the plane, since he was campaigning in Minnesota for Wellstone. That rumor was quickly dispelled, and Kennedy later appeared with Dayton to pay tribute to Wellstone

Wellstone announced recently that he had been diagnosed with multiple sclerosis, but said he would not let it deter him.

Before he acknowledged his disease publicly, denizens of Capitol Hill had noticed that he was walking with a limp. He chalked it up to long days at work.

The old-school traditional Democrat had broken a promise to stop running for office after two terms, saying that Minnesota needed a voice of opposition to the Bush administration.

Wellstone cast his vote earlier this month against legislation to authorize the use of force in Iraq -- the only Democrat facing a tough re-election to go against Bush on the issue.

However, by all accounts, he was considered a man of incredible integrity and one of the most straightforward and honest brokers in the Senate. Observers say he would never look at poll numbers to determine his policy positions.

"He never blinked," said former Republican Rep. John Kasich, who added that dying while serving one's country is "the ultimate sacrifice."

"It's pathetic that he would have to die" this way, said Sen. Pete Domenici, R-N.M, who had been working with Wellstone for a Mental Health Parity Act for about three years.

The bill, which would give mental health conditions the same insurance protections as physical conditions, will be dedicated to him, Domenici said.

Wellstone had also been an advocate of any bills that would help disadvantaged Americans. He crusaded for homeless veterans and railed against a bankruptcy reform measure before the Senate this summer that he said would benefit banks, credit card issuers, automobile finance companies and retailers at the expense of people who "now find themselves in brutal economic circumstances."

"Are single women with children deadbeats? This bill assumes that they are," Wellstone said in July before voting against the measure that was ultimately defeated.

This is the second election in a row in which a Senate candidate has died in a plane crash. In 2000, former Missouri Gov. Mel Carnahan, his son and campaign workers were killed when their plane went down in bad weather. The governor of Missouri appointed Carnahan's widow Jean Carnahan to fill the seat he won posthumously. She is now running to fill out the last four years of the term.

According to Minnesota law, the Democratic Party could nominate a replacement candidate to run. State Democratic Party spokesman Bill Amberg said he was confident the party would be allowed to offer a replacement.

State officials were researching whether Wellstone's name would remain on the ballot, or whether independent Gov. Jesse Ventura or state Democrats could appoint a replacement to serve in the upcoming lame-duck session of Congress between Election Day and the arrival of new members.

State law allows the governor to fill a vacant Senate seat, but also allows a political party to appoint a replacement in the event of a death of a nominee. The name must be offered within seven days of the death and at least four days before an election.

Ventura declined comment on what he would do about the ballot, saying only that he would not appoint himself to serve the rest of Wellstone's term.

Minnesota's senior senator was born to Russian immigrants Leon and Minnie Wellstone on July 21, 1944. In 1963, Wellstone married Sheila Ison, his high school sweetheart. They have two surviving children, David and Mark and six grandchildren.

Wellstone was a college civics professor before running for office. In 1990, in his first Senate bid, he campaigned across the state in a green bus, and stunned the political community by defeating Republican Sen. Rudy Boschwitz.

Fox News' Carl Cameron and Rita Cosby and The Associated Press contributed to this report.