Donald Trump is in trouble. You can't tell from his performances at his campaign rallies. The Republican presumptive presidential nominee remains bullish and combative, but the problems are there.

First he stirred up a controversy with comments about a judge hearing a civil case against him. Even though the judge was born in Indiana, Trump insisted he could not get a fair hearing from the man because he was of Mexican heritage.

The businessman said as he was going to build a wall to keep undocumented immigrants from crossing the Mexican border, the judge, an experienced and respected member of the legal community, would be biased against him.

His remarks, repeated in several media interviews, stirred the Republican establishment. House of Representatives Speaker Paul Ryan, the most senior elected Republican in the country, described the comments as "the textbook definition of a racist comment".

Yet, given that he'd finally endorsed the Republican nominee just a few days before, he insisted he still had his support.

Trump backs blocking gun sales to terror suspects

Let than sink in for a moment.

His most high-profile backer had essentially called him a racist, but was still going to try to have him elected as US president.

It was interesting that on the US media networks no senior Republicans popped up to support the nominee. Veteran US journalist Bob Schieffer said: "The silence is deafening."

Then there was his reaction to the shooting in Orlando.

As police counted the bodies, Donald Trump tweeted: "Appreciate the congrats for being right on radical Islamic terrorism, I don't want congrats, I want toughness & vigilance. We must be smart!"

Appreciate the congrats for being right on radical Islamic terrorism, I don't want congrats, I want toughness & vigilance. We must be smart! — Donald J. Trump (@realDonaldTrump) June 12, 2016

His critics from all sides of the political spectrum were angered, claiming that even in moments of national tragedy Trump remained solidly self-centered.

In a speech the next day, he took the opportunity to renew his call for a complete ban on Muslim immigration.

He made a similar call in December after a mass shooting in California and was criticised by many, including Republicans, who said the idea was not only unconstitutional, it was un-American.

In fact Paul Ryan - him again - said at the time: "This is not conservatism, is not what this party stands for, and, more importantly, it’s not what the country stands for."

Trump insisted, without any evidence, that people in the Muslim community had known in advance about the attacks in San Bernardino and Orlando and done nothing to stop them.

Again, no senior Republican backed Trump's ideas or appeared on the media to defend him.

Then on Tuesday, he tweeted again that he was going to meet the National Rifle Association (NRA) to discuss implementing new gun legislation after the Orlando shooting.

His main concern was "no-fly no-buy", the idea that anyone on a US Government terrorist watch list or no-fly list should also be barred from buying a gun.

It's a proposal put forward by many Democrats, including President Barack Obama, who has called it a common-sense measure.

Obama slams Trump's Muslim ban call

The NRA, who had endorsed Trump at its national convention just two weeks ago, said it was happy to meet. But many supporters were furious the Republican nominee would even consider changes to gun legislation.

Right-wing blogger Erik Erikson wrote: "This is a terrible idea and a flat-out cave by Donald Trump. You cannot deny constitutional rights to American citizens because the government is suspicious of you."

If all that wasn't enough, new opinion polls show that firstly Trump is falling behind Hillary Clinton in the national polls.

And another poll says Trump's standing with the American public has deteriorated significantly. A man who has already borne the burden of being the least popular presidential candidate in modern American political history pushed that barrier a little further. Now 70 percent of the electorate view him negatively, 56 percent feel "strongly unfavourable".

There's a long way to go until the election, but the events of the last two weeks and the new polls tell the same story. Trump's in trouble.