Senator Marco Rubio, a Republican from Florida, has refused to rule out accepting future donations from the National Rifle Association (NRA), during a town hall meeting with survivors of last week's school shooting.
Proceedings became heated in the debate, televised by CNN, when Rubio was challenged by Stoneman Douglas High School senior and survivor Cameron Kasy to reject donations by the NRA, a powerful lobby group which wants the expansion of gun rights.
"I will always accept the help of anyone who agrees with my agenda," Rubio told Kasy.
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Moments before at the BB&T Center in Sunrise, Florida, Rubio had argued with Democrat Congressman Ted Deutsch about access to assault rifles.
"You would literally have to ban every semi-automatic rifle that's sold in America," Rubio said, prompting loud applause from the audience, which largely appeared to be in favour of gun control.
"Fair enough," Rubio told the crowd. "That is a valid position to hold."
NRA spokeswoman Dana Loesch appeared toward the end of the meeting alongside Broward County Sheriff Scott J Israel, who coordinated the response to last week's attack.
She opened by arguing that the background check system is flawed, before blaming shootings on mental illness and criticising law enforcement.
