IOWA CITY (AP) — Sen. Tom Harkin abandoned plans Tuesday to donate his papers to a namesake institute at Iowa State University after a power struggle between his supporters and university leaders over the scope of its research.

Harkin said in a letter released Tuesday evening that he would not give papers covering his 30 years in the Senate and 10 years in the House to the Harkin Institute of Public Policy at Iowa State, his alma mater. Harkin agreed to donate them before the institute was created in 2011, but he said he was backing out after it became clear he could not trust university leaders to allow unrestricted academic freedom at the institute.

“I regret that this did not work out as we had all hoped at the beginning,” he said.