U.S. Senator Susan Collins delivered the 2015 Mitchell Lecture on April 9, discussing the importance of moderation and bipartisanship in order to to make progress in national government.

“The flip side of that premise, of course, is how the hyperpartisanship and incivility in Washington and throughout our nation elevate extremism and prevent progress,” Collins said.

The lecture followed Collins’s recent decision to decline, along with six other Republican senators, siding with the rest of the party on sending a letter to the Iranian government attempting to undermine the White House’s nuclear discussions with that country.

“I decided not to sign that letter because I thought it was completely inappropriate,” Collins said in a Q&A session after her lecture. “I did not think as a senator that I should be writing to the ayatollah in Iran when the president was engaged in very sensitive negotiations.”