Donald Trump at a National Press Club luncheon in May. (Jewel Samad/AFP/Getty Images)

Donald Trump is back, and he's thinking* of running for president in 2016. Again*.

And his enablers are only so happy to help him out. Trump was given an invitation to the Iowa Freedom Summit this weekend -- perhaps out of affection but more likely out of a desire for the attention Trump inevitably brings.

At the event, he appeared alongside legitimate politicians and prospective GOP presidential candidates, with the best and most influential political journalists in the country sitting through nine hours of speeches. (Yep, nine hours. Wouldn't want to leave anybody out, apparently.)

Trump promptly used the platform he had been given to do what he does best: promote The Donald. But he also found time for a relatively new endeavor -- bashing two of the more likely 2016 GOP nominees, Jeb Bush and Mitt Romney.

“It can’t be Mitt; he ran and failed," Trump said, noting Romney's Obamacare-esque Massachusetts health-care law and his "47 percent" comments. Then Trump added a striking bit of revisionist history: "He choked. Something happened to him in the last month. He had that election won."

(Reality check: There was absolutely no point at which Romney was the clear favorite in the 2012 election. But this is hardly the first time Trump has shown his lack of political acumen.)

For good measure, Trump then turned to Bush, whom he attacked for supporting comprehensive immigration reform and the Common Core education standards -- a total non-starter among groups like the one he spoke to Saturday. "The last thing we need is another Bush," Trump said.

There is a point at which Trump's political apprenticeship (see what we did there?) stops being a relatively harmless sideshow and he starts becoming a potential problem for Republicans. Others would argue that this ship has sailed already, and that's fair. But it has become abundantly clear this whole thing has diminishing -- if any -- returns for the Republican Party.

It's one thing for Trump to espouse discredited theories about whether President Obama was born in the United States; it's another for Trump to start attacking fellow Republicans and fomenting intra-party feuds during his regular media appearances. One is bad enough without the other.

This is all even more striking because Trump was a Romney guy in 2012 -- even during the primary season. He endorsed him in early February, before Super Tuesday, raised money for him and did robo-calls.

It's no secret why Trump is doing this. He's not getting as much attention for his potential presidential candidacy this year, and there's no better way to get attention than to start fighting with your own party. He has been doing this for years, saying he was considering a 2012 presidential bid and a 2014 New York governor bid. He even toyed with a third-party bid in 2000. People aren't paying as much attention this time, so he needs to up the ante.

He's just not serious. He can't even name a county in Iowa.

Republicans -- even in the party establishment like Romney -- have played nice with Trump for a long time, not wanting to inflame the portion of the base he has sway over. That made political sense when he was an early leader in polls of the 2012 GOP primary polls and the birther movement was still a thing; today that's not the case. Trump has moved from a sideshow with a base to a sideshow without a base. It's why there's no real push for him to run for president (outside of his own head, of course).

It might be time for events like the Iowa Freedom Summit to stop inviting him. And for a Republican Party that is trying to broaden its appeal going forward, dealing with its Donald Trump problem would be a pretty good start.

* Not really. See here.