Washington (CNN) Sen. Marco Rubio defended accepting contributions from the National Rifle Association, telling a Parkland school shooting survivor that the NRA's influence comes from the membership it represents.

"The influence of these groups comes not from money," the Florida Republican said at CNN's town hall "Stand Up: The Students of Stoneman Douglas Demand Action" on Wednesday night in Sunrise, Florida. "The influence comes from the millions of people that agree with the agenda, the millions of Americans that support the NRA."

Jeers from the crowd overwhelmed the discussion at several moments as Marjory Stoneman Douglas High School student Cameron Kasky pressed Rubio not to accept donations from the pre-eminent opponent of gun control legislation.

"The positions I hold on these issues of the Second Amendment, I've held since the day I entered office in the city of West Miami as an elected official," Rubio said. "People buy into my agenda, and I do support the Second Amendment."

When Kasky kept asking Rubio whether he would continue to accept the NRA's contributions, the senator said that was the wrong way to look at it and that people "buy into" his agenda.

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