President Trump attacked Sen. Susan Collins of Maine on Friday for her decision to not support his latest U.S. Supreme Court nominee, Amy Coney Barrett.

In a tweet shortly after 8:30 a.m., Trump referred to a “nasty rumor” that Collins will not vote to confirm Barrett to replace the late Justice Ruth Bader Ginsburg. It’s not a rumor – Collins has said publicly that she doesn’t support confirming a nominee this close to the election because of the precedent set four years ago when President Barack Obama nominated Merrick Garland and Senate Majority Leader Mitch McConnell refused to hold a hearing on Garland’s nomination. Collins has said her decision is in no way a reflection of whether she believes Barrett to be qualified.

There is a nasty rumor out there that @SenatorCollins of Maine will not be supporting our great United States Supreme Court Nominee. Well, she didn’t support Healthcare or my opening up 5000 square miles of Ocean to Maine, so why should this be any different. Not worth the work!

— Donald J. Trump (@realDonaldTrump) October 16, 2020

Collins’ campaign spokeswoman, Annie Clark, issued a measured response to the president’s criticism.

“Senator Collins works with this president – like she does with all presidents – when she thinks he’s right, and she opposes him when she thinks he’s wrong,” Clark said in a statement. “It’s what she’s always done, and it’s what she’ll continue to do.”

In his tweet, Trump also appeared to reference Collins’ lack of support for overturning the Affordable Care Act three years ago. She was one of three Republican senators – along with Lisa Murkowski of Alaska and the late John McCain of Arizona, who voted against that proposal, which was narrowly defeated.

The president further criticized Collins for not supporting his “opening up 5,000 square miles of Ocean to Maine,” referring to his decision this year to open the Northeast Canyon and Seamounts Marine National Monument to commercial fishing. The monument was established during the Obama administration.

In response to Trump’s opening of the monument, Collins said she has worked with Maine fisherman on a host of issues, including trade, regulations on protecting right whales and on economic relief necessitated by the pandemic.

“The federal government should direct its focus to resolving these challenges rather than reopening the debate over this national marine monument,” she said in a statement.

Also, the ocean area Trump referenced mostly affects fishermen farther south, in Massachusetts, Rhode Island and New York.

Trump is hardly shy about attacking fellowing Republicans who deign to speak out publicly against him, but it’s been rare for him to go after Collins directly. It’s also unclear why the president chose to go after Collins on this issue as it’s all-but-certain that the Republican-led Senate has the votes to confirm Barrett before the election since only Collins and Murkowski have said they will oppose the nomination. Trump did not tweet about Murkowski on Friday.

Collins was the deciding vote on another of Trump’s Supreme Court nominees, Brett Kavanaugh, in 2018 – a decision that contributed to an erosion of her support among Mainers, women in particular.

She acknowledged last month that her vote to confirm Kavanaugh “was going to hurt me politically, but there’s no sense in being in the Senate if you’re not willing to stand up and do what is right during those difficult times.”

Collins also voted to acquit Trump of impeachment charges in February, a move that emboldened critics further and surprised some who thought she might go against her party.

The president’s harsh comments come less than three weeks before Election Day, when both he and Collins face stiff challenges. Collins, who is seeking her fifth term, trails in several public polls behind Democrat Sara Gideon, and the U.S. Senate race in Maine could determine whether Republicans retain control of the Senate.

Trump, meanwhile, trails former Vice President Joe Biden in Maine by an average of 11 points in public polls, although the race is much closer in the state’s 2nd Congressional District. Maine is one of only two states that splits its electoral votes between congressional districts. In 2016, Trump lost the state as a whole but won the 2nd District.

The Senate race in Maine has featured a record amount of fundraising and and spending, both from the campaigns themselves and from various political action committees supporting or opposing the respective candidates.

Collins has largely avoided talking about Trump during her campaign and has refused to say whether she supports his re-election. Four years ago, she wrote a lengthy op-ed in the Washington Post in which declared him “unfit” for office. Since his election, she has supported many of his policies and spoken out against others and often is the Republican member of Congress most likely to criticize the president’s divisive rhetoric.

Her re-election prospects this year could hinge on whether she receives enough support from unenrolled voters, and distancing herself from Trump – or him distancing himself from her – may help. On the other hand, Max Linn, a Republican-turned-independent who also is running for Senate, has criticized Collins for not being sufficiently pro-Trump. He’s polling in the low single digits.

Ron Schmidt, a political science professor at the University of Southern Maine, said he believed Trump was “just lashing out” with his tweet Friday morning.

“It won’t gain him anything, but it probably won’t cost him anything,” Schmidt said. “Let me put it this way, if he fails to get our fourth electoral vote, it won’t be because he insulted Sen. Collins. If it has any effect on her – hurting her with Trump GOPers in Maine, helping her with independents – I doubt it will be decisive.”