ACT leader David Seymour was met with chants of "Kill the bill, kill the bill" when he walked out of the Beehive for a brief appearance at Parliament's forecourt, before waving to the crowd and returning into the building.
More than 35,000 people have gathered as the Hīkoi mō te Tiriti overflows from Parliament's grounds and onto nearby Wellington streets.
Seymour says it was important for democracy to go outside and face the hīkoi gathered at the front of Parliament.
Toitū te Tiriti spokesperson Eru Kapa-Kingi told the crowd "Māori nation has been born" today and that "Te Tiriti is forever".
Seymour, the Treaty Principles Bill architect, had previously said he supports the right to protest, but thinks participants are misguided and have a range of different grievances.
Having faced the protesters on Tuesday afternoon, flanked by police and members of diplomatic security, he said it was useful to listen.
"I felt these people have made a long journey to Parliament and we as parliamentarians should be there to hear them.
"I have to say it was quite difficult to hear a lot of what was being said, but nonetheless I thought it was important to be out there."
Seymour was flanked by police and members of diplomatic security.
He added he would have liked to have gone out and spoken.
Watch the moment in the player above, and see what those in the hīkoi had to say below:
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