"Some of your Senate colleagues, as you know, are concerned that President Trump is preparing to fire [Special Counsel Robert] Mueller or Mueller and [Deputy Attorney General Rod] Rosenstein," CNN's Jake Tapper said to Sen. Marco Rubio (R-Fla.) Sunday, then asking: "How would you react if he did?"

"Well, first of all, that's not going to happen," Rubio replied, addressing Mueller's investigation into possible ties between Trump and Russian election meddling. "And here's what I would say: The best thing that could happen for the president and the country is a full and credible investigation. I really, truly believe that. If we want to put all this behind us, let's find out what happened, let's put it out there, and let's not undermine the credibility of the investigation."

Rubio expressed full confidence in Mueller's integrity, a point he reiterated in another interview Sunday, this one on CBS' Face the Nation. The Florida senator also addressed Trump and the Russia investigation on NBC's Meet the Press, where he acknowledged "the president's pretty fired up about this" but maintained Trump's strong feelings "in no way [will] impede any of this work from continuing."

Watch an excerpt of Rubio's CNN appearance below. Bonnie Kristian

Two police officers, Matthew Baxter and Sam Howard, were shot in Kissimmee, Florida, Friday night while responding to a report of suspicious activity. Baxter was killed and Howard remains in "grave critical condition." The suspected shooter is in custody and three other people have been detained; details about their identities or the motives behind the attack have not been released. Kissimmee police are still searching for one more person.

President Trump promptly tweeted after news of the attack broke:

Four other police officers were also wounded on duty Friday night, two in another part of Florida and two in Pennsylvania. One is in critical condition, while the other injuries are less serious. Bonnie Kristian

Boston city officials have announced a heavy police presence will be on hand to contain potential violence at competing protests scheduled Saturday in Boston Common, the city's most historic park.

What those officers — and protesters — will encounter is unclear. The event started with a permit for up to 100 people with the stated purpose of demonstrating for free speech, but counter-protests were planned when other local activist groups, including Black Lives Matter, noticed two of the scheduled speakers have ties to the alt-right, and one of those two attended the white nationalist rally in Charlottesville.

"We're expecting about 20,000 to 30,000," said one counter-protest organizer, Monica Cannon. "We plan to send a really strong message that ... you don't get to come here and do this."

A previous demonstration by Boston Free Speech, the group that applied for the original permit, was organized in a different park in Boston earlier this year. Also billed as a pro-Constitution event, many attendees were affiliated with alt-right and white supremacist groups, and speakers included one Augustus Invictus, who told his audience to prepare themselves to fight a second Civil War. Boston Free Speech abridged Saturday's schedule in response to the planned counter-protests. Several of the more controversial speakers, including Invictus, are no longer on the docket. Bonnie Kristian

Investor Carl Icahn announced Friday that he had stepped down from his advisory role to President Trump. Icahn was counseling the president regarding regulatory reform issues, but he said he was announcing his resignation after a conversation with Trump earlier Friday in which the president "agreed" with his decision.

In a letter to Trump to "confirm" their conversation, Icahn emphasized that he "never had a formal position" with the White House. "I chose to end this arrangement (with your blessing) because I did not want partisan bickering about my role to in any way cloud your administration," Icahn wrote. "I sincerely regret that because of your extremely busy schedule, as well as my own, I have not had the opportunity to spend nearly as much time as I'd hoped on regulatory issues."

Icahn has long been a supporter of Trump's, writer Sarah Kendzior notes. Read Icahn's full letter announcing his resignation below. Kimberly Alters

President Trump fired his chief strategist Stephen Bannon on Friday, and it sure seems like no one in the White House will be torn up over his departure. Shortly after the news broke, Politico published a particularly brutal post-mortem of the Bannon era, with Bannon's now-former colleagues ripping the staunch conservative's tendency to inflame personal tensions:

[Chief of Staff John] Kelly didn't understand what Bannon did, why he had a PR portfolio, why he seemed to cause so much trouble with colleagues and why he was so widely disliked. He asked many questions about Bannon in his early days at the White House and found widespread disdain.

"No one liked him," a senior White House official said. "People didn't know what he did other than stab his colleagues in the back." [Politico]

Bannon was a "disruptive force" who "wouldn't follow process" in the White House, another unnamed White House official said. Nevertheless, he was apparently still "in denial" about his impending ouster, even as rumors of his demise intensified this week.

Read more about Bannon's final days at Politico. Kimberly Alters

If you find it nearly impossible to keep up with the news these days, CNN's Brooke Baldwin has a handy summary of President Trump's past four weeks in office. Only, it takes Baldwin nearly three minutes to read through the entire list of bullet points.

"Let's all just take a moment, just remind you what has happened. Incredibly significant events, one after the other," said Baldwin. "In no particular order, President Trump in the last four weeks has: fires his chief strategist; fires his chief of staff; hires a new one; hires a new communications director; fires him — "

That would be enough for an entire summer, but Baldwin is barely getting started. Watch the entire recital below. Jeva Lange

There is a secret message waiting for readers of this resignation letter, penned by the members of the President's Committee on the Arts and the Humanities:

The first letter of each paragraph spells "RESIST," keen-eyed readers on Twitter discovered. Kal Penn, who sat on the committee, confirmed the Easter egg was intentional.

The entirety of the President's Committee on the Arts and the Humanities resigned Friday over Trump's handling of the protests in Charlottesville, Virginia. "We cannot sit idly by, the way that your West Wing advisers have, without speaking out against your words and actions," the committee wrote. "Ignoring your hateful rhetoric would have made us complicit in your words and actions. We took a patriotic oath to support and defend the constitution of the United States against all enemies, foreign and domestic."

Other eagle-eyed readers might have caught one other awkward thing about the letter: As Soledad O'Brien points out, first lady Melania Trump is the committee's honorary chair. Jeva Lange

Chief strategist Stephen Bannon is out at the White House, but in the words of The New York Times' Maggie Haberman, "Bannon is much more of a problem for the White House staff from the outside than inside it."

That's putting it mildly, at least if you ask people in the orbit of Bannon and Breitbart, the far-right publication Bannon might soon be returning to lead. In the words of Breitbart editor Joel Pollak, after all, this means #WAR.

Here are six dramatic quotes about the coming storm. Jeva Lange

1.

2. Bannon "has a 'killing machine' in Breitbart News." [Axios]

3. Breitbart and Bannon will go "thermonuclear" against the "globalists." [Axios]

4. "Get ready for Bannon the barbarian." [Axios]

5.

6. "If they get rid of Bannon, you know what's gonna happen? The motherlode. If Bannon is removed, there are gonna be divorces, because I know about the mistresses, the sugar babies, the drugs, the pill popping, the orgies. I know everything. If they go after Bannon, the mother of all stories is gonna drop, and we're just gonna destroy marriages, relationships — it's gonna get personal." [Alt-right leader Mike Cernovich via The Daily Beast]