Nearly 3,700 Republicans from all 66 South Dakota counties — including former state lawmakers, business and civic leaders and others — publicly support his re-election bid, Daschle told reporters at a news conference.
"I am honored. I am humbled by the endorsement from people I've admired for a long, long time," said Daschle, who is seeking his fourth term.
Among about 20 Republicans who joined Daschle at the news conference were former Tea mayor Earl Jacobsen and former state lawmakers Kay Jorgensen of Spearfish and Don Frankenfeld of Rapid City. The three are co-leaders of a group called Republicans for Daschle Committee.
Dick Wadhams, Thune's campaign manager, said many of those campaigning for Daschle have a political agenda that fits with that of the Democratic incumbent.
"These are very, very liberal Republicans who are pro-abortion and pro-gay marriage," Wadhams said.
When asked to be more specific, Wadhams said he was "just making that observation."
Daschle, who served in the U.S. House before moving to the Senate, said many of the Republicans backing his campaign believe his continued leadership will give South Dakota an edge.
They have told him the state depends on his political clout to help win funding for farm and water projects and draw attention to the state's agricultural concerns and other issues, said Daschle.
"This election is about what's best for South Dakota," and not about which party comes out the winner or loser, he said.
Daschle said he has spent his entire political career working on legislation aimed at helping South Dakota become an even better place to live and work. With his experience in Congress and leadership position in the Senate, Daschle said he can continue that work.
Wadhams accused Daschle's campaign of using "backhanded" means to find Republicans willing to back the Democrat.
According to Wadhams, a letter went out to a large group of Republicans noting that if it wasn't returned to the Daschle campaign, the letter holder would be listed as a Republican for Daschle.
"That's kind of an underhanded way to solicit people's support," he said.
A copy of a letter provided to The Associated Press states:
"As part of the `Republicans for Daschle' group, my campaign will be publicly releasing your name, along with thousands of other South Dakota Republicans who support me."
It also says that if the recipients didn't want their names released or didn't recall being contacted about the group, they would get in touch with the campaign to have it removed.
Dan Pfeiffer, Daschle's communications director, said the letter was sent to confirm that those who were contacted had agreed to campaign for Daschle. It was not the first communication with those on the list, he said.
"I can understand why the Thune campaign is in a mild state of panic" over Republicans siding with Daschle, said Pfeiffer. "It speaks volumes about what Tom Daschle has done."
Although Republicans have signed onto his campaign before, it marks the first time the group has been so large and so many notable Republicans have agreed to stump for him, Daschle said.
When Thune unsuccessfully challenged Sen. Tim Johnson in 2002, Johnson announced a group of more then 780 GOP supporters, said Daschle.
Frankenfeld, who ran for U.S. House against Johnson in 1990 and lost, said he has voted for Thune in four separate elections and never voted for Daschle. He said he changed his mind this time because he believes Daschle can do the most for the state.
"It's all about what's right for South Dakota," said Frankenfeld.
Jorgensen said the future of her children, ages 19 and 22, played a big role in her decision to campaign for Daschle.
A 12-year veteran of the Legislature, Jorgensen said she wants them to have the same chance to live and work in their home state as she has had. "Tom Daschle represents a positive force to me for our state," she said.