Intensifying a dispute with Wellstone Action, the nonprofit created to honor the late U.S. Sen. Paul Wellstone, his sons David and Mark Wellstone this week asked the organization’s top donors to press it to remove their family name and answer financial questions.

“We plead with you, as a core funder of Wellstone, to help us make that happen, by using your own influence … in any and every way possible,” said the letter, which was mailed Tuesday to the Ford Foundation, George Soros’ Open Society Foundations, Proteus Fund and others.

The siblings’ letter noted “swirling dark clouds of controversy, unanswered questions, and doubts about the very survival of the organization,” which trains candidates and campaign workers.

In a statement, Wellstone Action board member Jeff Blodgett called the letter’s assertions “specious.”

Claims of financial mismanagement, he said, “are red herrings, perhaps to create a smoke screen around some other motives on their part.”

Former board members have said the dispute began when they raised questions last year about $200,000 in spending and a sharp drop in the cash balance. Blodgett said the group hired an outside auditor who “found absolutely nothing wrong.”

The audit was not shared with the Wellstones or former board members, Blodgett said, because they had refused to sign a confidentiality agreement. The Wellstones’ letter said they had offered to sign such an agreement, but it was never sent to them.

Blodgett said the organization will be rebranded “in a way that is true to the work and values that Wellstone Action is well-known for” and said he is “saddened that this fight continues in the public eye.”

David Wellstone said Wednesday that “in our hearts, we just want the name gone immediately.” He said the spending issue must be resolved. “We’re trying really to take the high road and just clean this up,” he said.

Wellstone Action is “no longer representing our parents’ legacy and so Dave and I would really like to see the name removed sooner rather than later,” Mark Wellstone said Wednesday. He has no reason to think anything inappropriate occurred, “but we’re super, super perplexed as to why we can’t get any answers,” he said.

Rick Kahn, the longtime Wellstone Action treasurer who was removed from the board last November, said Wednesday, “We leave it to the funders to reach their own decisions about whether an appropriate response to this request from Dave and Mark and to the circumstances is to suspend or withdraw their financial support.”

Conflict on Wellstone Action’s board became public last month when the group said it had decided to end its relationship with the brothers; they were voted off the board Feb. 16. Three other board members, including Kahn, left in recent months after raising financial questions.

Before the brothers’ exit, they said in the letter, they were near an agreement to resign voluntarily if the board pledged to change Wellstone Action’s name by the end 2018.

In their letter, the brothers said “this is no longer a conflict about finances, and never was a conflict about mission. It is about core values. The values of Paul and Sheila Wellstone who would never have treated anyone, even their worst enemies” in the way that the remaining board members “treated and betrayed us, and our friends.” Their parents, who were widely revered by Minnesota DFLers, died in a 2002 plane crash.

In a statement posted Feb. 23 on its website, Wellstone Action said its original mandate from Paul and Sheila Wellstone “is a legacy that we are proud to have in our DNA.” The statement added that “the progressive movement also looks different today than it did when we first started.”