On the campaign trail, however, they sound more like compatriots, both determined to defeat the same foe: Republican Gov. Mike Rounds.
Only one will emerge as a winner in the June 6 Democratic gubernatorial primary. Anyone who expected the two men to battle each other at Thursday night's Clay County Democrats' annual banquet in Vermillion may have been disappointed.
The two men were civil to each other, saving their critical remarks for the Rounds Administration and the Republican majority in both houses of the state Legislature.
Billion, a retired orthopedic surgeon from Sioux Falls, said South Dakota spent less for K-12 education this year than it did last year.
"Education is our future," he said. "The economic market looks to education, it looks to people. That's the main resource we have to deal with."
Despite that, he said, South Dakota continues to underfund education, noting that 80 percent of the state's public school districts have had to opt-out of South Dakota's property tax freeze to financially survive.
Billion says South Dakota also must adopt a new economic philosophy.
"We have to not try to attract new businesses from somewhere else based on working for low wages, but rather we have to grow our own businesses," he said.
Billion said he would also strive to make sure that health care is of high quality, is affordable, and is accessible for all South Dakotans.
"We have 90,000 people in South Dakota who today are uninsured," he said. "That's the first problem that we have to address. There are some positive things we can do if we all sit down and work together."
Wiese of Flandreau is best known as the former president of the South Dakota Farmers Union.
"People run for governor because they think they can make a difference," he said. "They run for governor because they see more hope and opportunity."
Wiese said he's seeking the office of governor because South Dakotans are looking for a leader they can trust.
He said many Democrats � even many in the banquet crowd � may have helped elect Bill Janklow to a total of four terms as governor.
"When that happened, you were looking for someone who made a decision and stuck with it," Wiese said. "That's what's sadly missing in Pierre today.
"This governor has fumbled more issues this year," he said, "than any governor I've ever seen."
He criticized Rounds for his stance on abortion, noting that first he vetoed the legislation, a year later he signed it, and then he said if it goes to a public vote, he would take no position on the issue.
"That's a weak governor," Wiese said. "That's a governor that can't make a decision."
Rounds, he said, "didn't lift a finger" in the last legislative session to substantially help fund education in South Dakota.
"We really lack leadership in this state," Wiese said. "We lack it in the Legislature from the Republican party, but they are only as good or as bad as the leader that they follow."
Wiese proposes full funding of education by using money currently in state reserve funds.
"The kids of this state and their parents should not have to sue the governor and the state of South Dakota (to fund education) and I intend to make that change," he said.
Wiese also calls for South Dakota to mandate the use of ethanol and other alternative fuels.