Bryan Cranston has hit out at Donald Trump, saying that the US president is beginning to resonate "less and less" with the people. The Breaking Bad star said he thinks the president has a "mental illness" with the country facing "something that we have never dealt with before" in Trump's presidency.

Cranston's comments came while speaking about his latest movie Last Flag Flying, in which he plays a Vietnam veteran who reunites with his two friends from his time in the army to bury one of their sons killed in the Iraq war.

"I never thought he [Trump] would be elected or make it through the first half a year. We are dealing with something that we have never dealt with before," the actor said in an interview with Channel 4 News.

"I think in all honesty and I don't mean this in a flippant way, I think that our president has an illness and I don't say that to try to draw out a laugh or anything. I think he has a mental illness."

When told he could not possibly know about Trump's "mental illness", Cranston replied: "That's why I use the words I think. I'm not a doctor; I'm not one of those people who wish for his downfall. I want him to be successful. I honestly do because if he is then that then means that my country has improved."

Cranston also talked about why "protest should be embraced" when asked about his thoughts on NFL players kneeling at games to protest against racial injustice.

"Historically, I don't think that any democratic country was formed without the sense of resistance and protest to oppression. So, we owe a great deal to the theory and execution of protest, we should embrace protest, not be afraid of it," Cranston said.

"We should be able to listen to protest, not turn a deaf ear to it. I think everybody tries to take ownership of what their beliefs are and impose that upon others and I think it's wrong.

"I think if you are protesting and you take a knee, I think that's fine. If you want to stand and put your hand over your heart and sing, I think that's fine."

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"I think if you are protesting and you take a knee, I think that's fine. If you want to stand and put your hand over your heart and sing, I think that's fine," Bryan Cranston said on NFL kneeling row. AFP/Getty