The statewide poll was conducted Monday through Wednesday for the Sioux Falls Argus Leader and television station KELO, also of Sioux Falls. Eight-hundred likely voters were polled by telephone. The margin of sampling error is plus or minus 3.5 percentage points in the poll, conducted by Mason-Dixon Polling and Research Inc. (search) of Washington.
A poll in February showed Daschle ahead by 7 percentage points. By May, the lead had shrunk to 2 percentage points.
Results from the most recent polling also show a growing negative opinion toward both candidates.
"It's basically still a tossup. A lot of different polls show it to be within a few points. Both men know that. That's why the rhetoric is so heated," said Christopher Maynard, an assistant professor of history and political science at Dakota State University.
Thune noted that Daschle has had trouble getting above 50 percent support in the past several Mason-Dixon polls.
"It's all going to come down to who catches the wind and turns out the vote," Thune said.
Daschle said he's getting broad, bipartisan support. "I'm pleased I'm leading a good candidate like John with less than 40 days to go."
The poll was conducted right after Thune and Daschle's tense exchange over the Iraq war on network television. Thune's unfavorable score in the polling jumped from 23 percent in May to 34 percent last week. Daschle's rose from 33 percent to 37 percent.
Rather than force the candidates to ease up, the higher negatives could mean both sides will simply turn up the heat, experts say.
"I doubt they'll get a whole lot more positive," said Joel Johnson, assistant professor of government and international affairs at Augustana College. "We'll probably see a fair amount of sniping back and forth."
Regardless of voters saying they don't like it, politicians know negative campaigning works, Johnson said.
"We want to see a battle," Johnson said. "It brings out qualities of character ... and shows a certain kind of courage. It doesn't matter if you turn off the hard-core supporters of the other person. If that gives you a little play with the undecideds, it may be useful."
Thune said he's not surprised that both candidates' unfavorable ratings have risen. "It's a pretty polarized race," he said.