(CNN) Republican Sen. Lisa Murkowski on Monday brushed off a series of critical tweets from President Donald Trump, including the President's promise to campaign against her when she's up for reelection.
Trump made the threat after Murkowski applauded a statement from former Marine Gen. James Mattis -- in which the former secretary of defense castigated Trump as "the first president in my lifetime who does not try to unite the American people" amid nationwide protests over the police killing of George Floyd -- as "true, and honest and necessary and overdue."
"I made the comments that I made," Murkowski told CNN on Monday. "I stand by them. Again, I think it's important that we have a president who is working to bring people together. ... And tone and words matter."
She added, "I cannot live in fear of a tweet. That's where I am now."
Mattis' statement last week came after federal law enforcement and National Guardsmen forcefully put down a peaceful protest outside the White House as Trump threatened to send in the US military to quell demonstrations across the nation in the wake of Floyd's death.
"We are witnessing the consequences of three years without mature leadership. We can unite without him, drawing on the strengths inherent in our civil society," Mattis wrote. "This will not be easy, as the past few days have shown, but we owe it to our fellow citizens; to past generations that bled to defend our promise; and to our children."
Mattis' forceful rebuke of Trump also forced other Republicans to respond.
Republican Sen. Susan Collins of Maine told CNN Monday she has read Mattis' statement and has "a lot of respect for him."
The Maine senator, who is up for a tough reelection, had declined to comment on his statement last week, saying she hadn't read it. She wouldn't elaborate Monday on whether she agreed with Mattis' criticism of the President.
"I already made my comments on the President's actions last week, so I really don't have anything more to add," Collins said, referring to her criticism of Trump's handling of the clearing out of peaceful protesters from Lafayette Square, after which he visited the nearby St. John's Episcopal Church for a photo opportunity with a Bible.
Collins has repeatedly refused to say if she is backing Trump's reelection bid.
Still, most Republican senators are dismissing the scathing criticism.
"It's Gen. Mattis' opinion, he's free to express it," Sen. Ron Johnson, chairman of the Homeland Security and Governmental Affairs Committee, told CNN. Asked again if he agreed with any of the criticism, Johnson said: "All I'm going to say about Gen. Mattis is I do respect him. He's a great American. It's his opinion to express it."
Leaving the floor on Thursday morning, Senate Majority Leader Mitch McConnell was silent when asked twice about Mattis' criticism, returning to his office and ignoring a reporter's questions.
The reaction reflects how many top Republicans on Capitol Hill have calculated that their fortunes in the 2020 elections rest in large part on Trump's performance at the polls. But Collins has yet to say publicly if she'll back the President's reelection bid.
She did not join Trump on his trip to her state Friday to participates in a roundtable with commercial fisherman in Bangor and then visit a medical equipment manufacturer, Puritan Medical Products, in Guilford.
That decision is part of the difficult balancing act she's had to navigate with Trump, who will be competing in the state this fall given that the state splits its electoral votes. Collins needs the backing of both Trump supporters and detractors to win in the Democratic-leaning state.
She's expected to face Democrat Sara Gideon in November.