Republican Sean Parnell, the Trump-backed candidate running to represent Pennsylvania in the Senate, announced Monday that he is dropping out of the race after losing custody of his children to his estranged wife.

Why it matters: Parnell was considered one of the frontrunners for the GOP nomination to replace Sen. Pat Toomey (R-Pa.), who is retiring at the end of his term after Trump endorsed the former U.S. Army Ranger in September.

Former President Trump's ex-personal lawyer Michael Cohen was officially freed from his prison sentence on Monday, CNN reports.

Why it matters: Cohen received the three-year sentence after pleading guilty to nine federal crimes, including lying to Congress in the Mueller investigation and campaign finance violations related to payments he facilitated to two women who claimed to have had extramarital affairs with Trump.

Former President Trump plans his first post-presidency book — "Our Journey Together," featuring 300+ official White House photographs. 

• Don Jr. tells Axios: "My father picked every single photo in this book, wrote all the captions, including some by hand."

Rupert Murdoch took a dig at former President Trump Wednesday, telling investors that conservatives can't move forward while Trump stays focused on the past.

Why it matters: Murdoch and Trump's relationship soured after the media titan, best known for his ownership of conservative-leaning outlets like Fox News and the Wall Street Journal, reportedly made the final call to give his team the go-ahead on calling Arizona for President Biden on election night last year.

The Wyoming Republican Party has voted to no longer recognize Rep. Liz Cheney (R-Wyo.) as a member of the GOP, AP reports.

Why it matters: Since voting to impeach former President Trump, Cheney has faced repeated criticism from Republicans and was removed from her leadership position in the House.

Chris Christie told me on "Axios on HBO" that he and former President Trump haven't spoken since before Jan. 6, when Christie frantically tried to reach his friend of 20 years — and Trump never picked up the phone.

Driving the news: "I tried to call him ... to give him advice on what I thought he needed to be doing to stop the violence," the former governor told me during our hourlong interview at his home in New Jersey.

Republicans — reshaped, controlled and defined by Donald Trump since 2015 — are slowly but surely charting a post-Trump ideology and platform.

Why it matters: Other than conservative courts, toughness on immigration and hostility toward modern liberalism, it's been impossible to specify the core and connective ideology of Republicans under Trump.  

House Intelligence Chairman Adam Schiff said Sunday that indicting former Trump adviser Steve Bannon was the right decision, adding that the move may "influence other witnesses" to cooperate.

Why it matters: The California Democrat's remarks on NBC's "Meet the Press" came after a federal grand jury on Friday indicted Bannon for failing to comply with a subpoena issued by the House select committee investigating the Jan. 6 insurrection of which Schiff is a member.

A reckoning is hitting news organizations for years-old coverage of the 2017 Steele dossier, after the document's primary source was charged with lying to the FBI.

Why it matters: It's one of the most egregious journalistic errors in modern history, and the media's response to its own mistakes has so far been tepid.

Former New Jersey Gov. Chris Christie, lacing up for a possible presidential run in 2024, told "Axios on HBO" he won't back down from a fight with former President Donald Trump, taunting his longtime friend for losing the last election.

• "I've never walked away from an argument, no matter who stood on the other side," Christie told me during a wide-ranging interview in New Jersey.

Why it matters: This is the first hand-to-hand combat of the 2024 Republican presidential race.