Quickly catch up on the day's news: Tuesday, October 24

A protester throws Russian flags towards Senate Majority Leader Mitch McConnell and President Trump as they arrive for the Senate Republicans' policy lunch in the Capitol on Tuesday.

(CNN)Here's what you might have missed on CNN today:

Tensions on Capitol Hill

The feud between President Donald Trump and Sen. Bob Corker escalated on Tuesday as the President was heading to Capitol Hill for tax negotiations. In an interview, Corker said he would not have backed Trump's presidential campaign and added that Trump has "great difficulty with the truth." The two then traded jabs on Twitter when Trump called Corker a "lightweight," and Corker responded to the "untruths" with #AlertTheDaycareStaff. On a lighter note, GOP Sen. Thom Tillis brought along popcorn to a tax reform lunch with Trump and Corker, where the feud was not discussed.
Adding to the tensions of the day, Arizona Republican Sen. Jeff Flake announced he would not seek re-election in 2018 in a historic, blistering critique of President Trump and the US political climate. He said he would rather retire than embrace Trump. Read Flake's full speech here.

    Niger ambush

    The four US soldiers killed in Niger were gathering intelligence on a terrorist leader when they were ambushed, officials said. Here's a timeline of what happened leading up to the attack.

    Travel ban

    The Supreme Court said Tuesday it won't hear oral arguments on the legality of Trump's travel ban.

      In other news

      -- A protester threw Russia flags at President Trump as he was walking to a meeting on Capitol Hill.

      -- Police are scouring a Tampa neighborhood for a possible serial killer after three people were killed in separate shootings the past two weeks.

      -- The World Series starts tonight in Los Angeles, and here's what baseball fans need to know.

      -- Billy Joel, 68, welcomes a baby girl with his wife Alexis Joel.

      -- Amazon Kindle announced an app update on Tuesday with new features, but it still won't let you buy books on an iPhone (only on Android).

      -- Despite the devastation from Hurricane Maria in Puerto Rico, San Juan is still listed among the best cities to visit in 2018. Here's why.