Jill Filipovic is a journalist based in Washington and the author of the book " The H-Spot: The Feminist Pursuit of Happiness. " Follow her on Twitter . The opinions expressed in this commentary are solely her own. View more opinion articles on CNN.

(CNN) Whose side is Lindsey Graham on? His constituents -- that is, the American people? Or the Trump family.

The ever more obsequious US senator from South Carolina has made his position clear: He's here to protect the Trump family, regardless of any alleged crimes, and regardless of the will of the American people, his Senate colleagues, or even the law. To Graham, defending the Trumps is more important than the pursuit of justice.

"You'd have to be an idiot as a lawyer to put your client back into this circus, a complete idiot," Graham told reporters . By Tuesday, Trump Jr. and the Senate Intelligence Committee reached a deal for the President's eldest son to appear before the committee behind closed doors in mid-June, a source told CNN.

But why in the world would the head of the Senate Judiciary Committee want to step up to undermine the intelligence committee's efforts to gather intelligence? Because Graham began disregarding right and wrong many months ago in favor of sucking up to the "First Family." Turns out the man who went from calling Trump a "kook," "crazy," and an "opportunist" "unfit for office," to doing the man's dirty work, knows a little something about opportunism.

JUST WATCHED Trump Jr. reaches deal with Senate committee to testify Replay More Videos ... MUST WATCH Trump Jr. reaches deal with Senate committee to testify 01:46

It's one thing to get rhetorically in line behind the leader of your party (that Graham doesn't publicly call the president "crazy" anymore may be cowardly, but it's also politics as usual). But Graham goes far further than that.

Recall last August when -- after months of Trump's derisive remarks about Graham's close friend, Sen. John McCain -- Graham told "CBS This Morning": "It bothers me greatly when the president says things about John McCain. It pisses me off to no end, and I let the President know it." McCain had died only days earlier. Fast forward nine months and Graham has positioned himself as one of Trump's greatest champions.

He was one of the loudest defenders of Brett Kavanaugh, Trump's pick for the Supreme Court, even after Kavanaugh was accused of sexual assault (Kavanaugh denies this). Graham dramatically and emotionally took the floor in Kavanaugh's confirmation hearing to upbraid Democrats for, he said, trying to ruin the guy's life. Graham now sucks up to the President about everything from his golf skills to his primary victory: "He beat me like a dog," Graham has said.

And now, he's also telling Trump's son -- who is only anywhere near the White House because of his wealthy, scammer father-- to evade a legitimate inquiry from a GOP-led committee. Graham's behavior is many things --including a total dereliction of his duties.

Now that Trump Jr. is reportedly testifying anyway, albeit in a limited capacity, one imagines he'll show, now that that the public is watching (he stood up the committee twice). The question is whether he'll take Graham's advice and stonewall.

JUST WATCHED CNN analyst: This is not the Lindsey Graham I know Replay More Videos ... MUST WATCH CNN analyst: This is not the Lindsey Graham I know 01:41

After all, Graham has backed Trump's claim that inquiries into the relationship between the Trump campaign and the Russian government's efforts to sway the election -- efforts we now know took place, and could happen again in 2020 -- are nothing but a "witch hunt" by a treacherous FBI. It is not Graham's job to repeat the President's cooked-up claims.

And given that Donald Trump Jr. was a key player in the campaign and engaged in communications with Russians and Russian assets (though he has denied wrongdoing), he is a necessary person for the Senate Intelligence Committee to interview.

Graham's toadying to Trump has been so over the top, and such an abrupt about-face, that the more conspiracy-minded on the left wonder what Trump has on Graham. It's probably something far simpler: an attack from the itchy-Twitter-finger President can mean reelection woes -- and Graham, who faces voters again in 2020 , wants to stay in office.

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The good news is that Graham's jaw-dropping sycophancy isn't going unnoticed. #LindseyGrahamResign is trending on Twitter, with folks across the country arguing that the South Carolina senator has made it clear he has abdicated his constitutional duties, and demanding that the senator step down. He won't, of course, but he needs to feel the heat for it.

Graham has tied himself to America's most disloyal family. Trump, his children and his flunkies will not come to Graham's aid if he's sinking, and make no mistake, that is where he's morally headed. Too bad. He tied his own foot to the anchor.