Republican Rep. Trey Gowdy sent waves through the GOP presidential race with word he will endorse Marco Rubio. The announcement — the Rubio campaign is touting Gowdy's upcoming trip to Iowa on Rubio's behalf — became the subject of angry tweets from Donald Trump supporters, who quickly denounced Gowdy as a RINO and a fake conservative. (Gowdy's rating from the American Conservative Union is a near-perfect 97 for the nearly five years he has served in the House.)

Trump, in a Sunday-morning appearance on "Fox and Friends," took a different tack. "I hope [Gowdy] does a better job than he did, frankly, at the Benghazi hearings, because they were a total disaster," Trump said, referring to the Oct. 22 hearing in which Gowdy, chairman of the Select Committee on Benghazi, called Hillary Clinton to testify. After the marathon hearing, some observers on both sides of the political aisle concluded that Republicans had failed to lay a glove on Clinton.

"[Gowdy] did not win with those hearings," Trump said. "It was not good for Republicans and for the country. I hope he does a lot better for Marco than he did with the Benghazi hearings."

Trump also tweeted Sunday morning: "Rubio finally gets an endorsement — from Benghazi loser Gowdy." In another tweet Trump said, "Face it, Trey Gowdy failed miserably on Benghazi. He allowed it to drag out and in the end, let Hillary get away with murder."

Like so many Trump attacks, it seems likely Trump's hit on Gowdy will incite denunciations of Trump for going after a conservative icon, and at the same time a debate on the substance of Trump's attack, in this case, the effectiveness of the Hillary Benghazi hearing. That's how Trump shaped the public conversation.

Polls have consistently shown that Trump does well with Republicans who are more moderate than the most conservative in the party. Given his campaign so far, it should be no surprise that he would attack Republican favorite Gowdy — and no surprise that he would base the attack on accusations about competence, rather than ideology.