Jennifer Horn, co-founder of the Lincoln Project and former chair of the New Hampshire GOP, told Boston Public Radio on Thursday it's "outrageous" that some Republican senators have already decided that they will not convict President Donald Trump in the impeachment trial. He has been charged with a single count of inciting a mob to storm the U.S. Capitol on Jan. 6.

"It's heartbreaking," she said. "It's frightening. It's stunning — that there is anybody at all in the United States Congress who doesn't see that Donald Trump incited an insurrection against the United States and should be convicted. It's outrageous that there are Republican Senators who have already decided they will not convict."

Horn, who has since left both the Republican Party and the organization she helped create, said the presentation by impeachment manager Rep. Jamie Raskin, D-Md., on the first day of the trial brought her to tears, and Democrats' case against Trump has successfully shown that he incited a mob to violence.

"They were there to kill the leaders of our country and try take over our government," she said.

On the future of the Republican party, Horn said she tried for four years after Trump was elected to try and reform the party from within, and she believed that his defeat would result in a groundswell of "courage" from Republicans who would distance themselves from the former president.

"That didn't happen," Horn said. "The opposite happened."

She lauded Rep. Liz Cheney, R-Wyo., for "going into the lion's den" on Fox News defending her vote to impeach Trump. "Republicans in the Senate need to walk behind her. They need to follow that example."

But Horn also cited the Republican caucus' support of Rep. Marjorie Taylor Greene, R-Ga., who has endorsed political violence and bigoted conspiracy theories, as a final straw that prompted her to leave the party.

"All of these Republican leaders said, 'OK, you may have defeated Trump, but we're going to take the ugliest, most horrible tenets of Trumpism and build the future of the Republican party on those.' And that's when I left," she said.

Horn said that it would be difficult and expensive to create an entirely new political party as an alternative to the current Republican Party.

"But that doesn't mean it isn't time to do it," she said.

Horn co-founded the Lincoln Project, a well-funded anti-Trump operation that worked to get President Joe Biden elected and present a Republican alternative to Trump. She has since left the group after revelations that fellow co-founder John Weaver was accused of sending unsolicited, sexually explicit messages to young men.

Horn said she was proud of the work the Lincoln Project did, but she left over "disagreements amongst the remaining co-founders about how to handle it," she said. "I'm not going to go any deepr than that right now. We had disagreements about how to manage it."

Horn said she did not know about the allegations against Weaver until they became public.

The Lincoln Project has said that it parted ways with Horn over demands that she be given a $250,000 signing bonus and a board seat on the organization, among other demands, according to The New York Times.

"All I will say is that I was engaged in aggressive contract negotiations to try and bring myself closer to fair compensation based on what other co-founders were earning," Horn said.

She denied that she left the organization over the contract dispute.

"I stopped attending the Catholic Church years ago because I could not right myself with how they handled abuse there," she said. "This is no different."

Jennifer Horn is the former chair of the New Hampshire Republican party, a co-founder of the Lincoln Project and an opinion contributor to USA Today.