Republican Sen. Susan Collins of Maine downplayed the threat of a re-election challenge in 2020, as lawmakers’ votes both for and against U.S. Supreme Court Justice Brett Kavanaugh in his contentious confirmation battle generate political backlash.

Collins, who voted for Kavanaugh in what she termed one of her hardest decisions ever, said in response to a question about a potential challenge from former U.S. National Security Adviser Susan Rice that she did what she thought was right. And besides, Collins said, Rice doesn’t really reside in her state.

“Her family has a home in Maine, but she doesn’t live in the state of Maine,” Collins said on CNN’s “State of the Union.”

On Friday, Rice responded “Me” to a tweet from another former Obama-era State Department official, Jen Psaki, asking who would like to make a Senate run in Maine. Rice, who also was a U.S. ambassador to the United Nations under Obama, later tweeted that she was “not making any announcements” but was “deeply disappointed” in Collins.

The exchanges came as the end of the bitter Senate battle over Kavanaugh’s confirmation became fodder for questions about political ramifications in the 2018 midterms and beyond. A crowd-funded campaign has raised millions of dollars for Collins’s eventual challenger, while former Alaska Gov. Sarah Palin suggested on Twitter that she could face Sen.Lisa Murkowski, the sole Republican opponent of Kavanaugh’s confirmation.

Sen. Heidi Heitkamp, a Democrat from North Dakota seeking re-election in November who voted against Kavanaugh, said in an interview for “60 Minutes” that she had no doubt supporting the nominee would have been “politically expedient,” according to a transcript provided by CBS.

The latest polls show Heitkamp trails her Republican opponent, Rep. Kevin Cramer, by double digits ahead of the Nov. 6 midterm election in a state Trump won easily in 2016. As recently as June the Senate race had been a statistical tie.

Collins on CNN said Rice’s words were ironic, because when Rice was nominated by Obama in 2009 to be U.N. ambassador, she “pleaded with me to introduce her” before the Senate Foreign Relations Committee, even though they weren’t acquainted.

On Sunday, Rice, who was born and raised in Washington, retweeted a posting about a 2009 press release from Collins announcing that she’d introduced Rice to committee and citing her “strong ties to our state.”

Rice’s grandparents emigrated to Maine, and her mother was raised there, according to the release.

Collins decried a move by political opponents to donate millions of dollars to a potential 2020 opponent in the wake of her decision.

“This is a classic quid pro quo as defined in our bribery laws,” she said on “60 Minutes.”

Collins revealed Sunday on CNN that Kavanaugh’s angry rebuttal to allegations by Christine Blasey Ford that he had attempted to rape her when they were teenagers helped to sway her vote. Heitkamp, by contrast, called the testimony a disqualifying factor — especially what she termed his “jaw-dropping” questioning of Democratic Sen. Amy Klobuchar of Minnesota.

“I found his performance to be disturbing,” Heitkamp said on “60 Minutes.”