''This is such an incredible event of people, American people. There's people selling food, people selling Trump T-shirts, media everywhere,'' he said.
''I've just walked past the BBC live broadcast just to my left. To my right there's another group of people in a separate protest against Trump, in front of me there's a line of Secret Service people.''
Mr Muller spoke to the Bay of Plenty Times while walking to the convention centre ahead of tonight's events, where Trump was expected to finally speak and a lead up of speakers during the week.
Mr Muller said he was privileged to be invited and hosted by the Republican Party and because he was an observer, did not hold a view on who he would prefer as a candidate.
''I have no view at all. We are here as observers, that's the important thing. I just look at this almost carnival of democracy in disbelief.
"It's absolutely extraordinary. I've never seen anything like this in New Zealand."
Mr Muller and Mr Ross will also attend the Democratic Party rally next week.