When He’s Right, He’s Right
By 
Trump’s response to Rubio getting the coveted Trey Gowdy endorsement is actually pretty acute:
Probably not, which is why this is an excellent demonstration of Rubio’s problem, and the problem the GOP is facing as the actual voting approaches. While everyone waits for the voters to finally figure out that they ought to be supporting Rubio, the only candidate who at the moment looks like he might be able to defeat Donald Trump is Ted Cruz. From the perspective of the party’s fortunes in the general election, that would be sort of like being cured of your electoral syphilis by contracting gonorrhea.
On one hand, it’s understandable that the Rubio campaign would try to make a big deal out of Gowdy’s support, since Republican politicians have been stingy with endorsements this year and Gowdy is well-liked among his colleagues on Capitol Hill. But when Trump dismissed the endorsement by saying that Gowdy’s Benghazi hearings were “a total disaster,” you could almost hear Republican voters nodding in agreement. The special committee was just one more iteration of the pattern that has Republican voters so disgusted with their Washington leadership: touted as the vehicle to bring down Hillary Clinton, it ended up backfiring and doing nothing but make Republicans look foolish. So once again, Capitol Hill Republicans overpromised and showed their constituents that they’re ineffectual. It’s hard to imagine that too many base voters, in Iowa or anywhere else, are going to say, “Well, if Trey Gowdy likes Marco Rubio, that’s good enough for me.”
Yup. For many months conservative talk radio listeners were told that Hitlery Clinton personally ordered the attacks on BENGHAZI! to cover up for the murder of Vince Foster or something, and just wait until she has to appear before Congress. Getting Gowdy’s support, if it means anything to a rank and file voter at all, will just remind them that Gowdy’ hearings were an embarrassing shambles. And while it’s not Gowdy’s fault that there was no evidence of any wrongdoing on Clinton’s part, good luck telling that to people who were sold yet another bill of goods and never think to wonder why the promises made by Tea Party leaders never seem to work out. None of this means that Rubio can’t win the nomination, but this isn’t going to help.