ST. PAUL (AP) — A liberal campaign organization dedicated to the late Minnesota Sen. Paul Wellstone is pushing out the senator’s two sons over differences in how the organization should run.

Wellstone Action informed David and Mark Wellstone on Wednesday that they would be voted off the governing board in the coming days, following what group leaders described as months of friction. They said the Wellstones have pushed repeatedly to shift focus from training progressive candidates and campaigns to more aggressive issue advocacy following Donald Trump’s election as president.

David Wellstone did not immediately respond to messages seeking comment on his ouster. A working phone listing could not be found for Mark Wellstone.

Co-founder and board member Jeff Blodgett, who was Paul Wellstone’s campaign manager, told The Associated Press the “necessary but sad step” of removing the brothers from the board comes after months of tension. He said the brothers have asked that the group no longer use the family name.

“It’s difficult, personally and professionally for us,” Blodgett said.

The Wellstone brothers and Blodgett formed Wellstone Action after Paul Wellstone’s death in a plane crash days before the 2002 election. It has trained more than 90,000 candidates and campaign managers for races ranging from school boards to legislative and congressional offices. The organization’s flagship program is Camp Wellstone, which holds three-day boot camps to train progressive candidates, campaign workers and organizers how to win office and make change.