Democratic presidential candidate Julián Castro criticized President Trump's tactics in trying to negotiate peace between the Taliban and Afghan leaders through a planned, and then canceled, secret meeting at Camp David.

"This is the worst president when it comes to negotiating, I think, that we've had in a very long time," Castro said Sunday on NBC's "Meet the Press."

"It's another bizarre episode. It's more of this erratic behavior that people are tired of," Castro added.

The former Housing and Urban Development secretary said Trump's latest antics were "bizarre" for two reasons.

Julián Castro on President Trump saying he called off Afghan peace talks with the Taliban: “It's another bizarre episode. It's more of his erratic behavior that people are tired of and that's one of the reasons I believe that he's going to lose in 2020” #CNNSOTU pic.twitter.com/ZC4e0oNOUT — CNN Politics (@CNNPolitics) September 8, 2019

"First of all, I think like most Americans, I don’t know what to believe anymore, what comes out of the mouth or the tweet of this president," Castro said.

The Democrat said he's still looking for confirmation "that an actual, physical trip to Camp David was planned."

"But if it was, if it had been planned, that's bizarre as well. Even though I do support negotiated political settlement there that will increase stability and make sure Afghanistan is not used as a base of terrorist operations, it's very odd to invite a terrorist organization like that to Camp David. That's not in keeping with the way that the United States negotiates," Castro said. ADVERTISEMENT

Similarly to other Democrats, Castro said he could "draw a straight line" between the canceled Taliban meeting and Trump's negotiating with North Korea.

"He has elevated Kim Jong Un Kim Jong UnNorth Korean leader Kim apologizes over killing of South Korean official Pelosi knocks Trump over refusal to commit to peaceful transfer of power Satellite images indicate North Korea preparing for massive military parade MORE with three summits now even though in the first summit, the Singapore summit, Kim Jong Un promised that North Korea would give to the United States an inventory of its weapons so that we could sue that as a basis for future negotiations they never did that and still at the same time theres a second summit and third summit," Castro said.