A Democratic Party and Planned Parenthood volunteer allegedly threatened to kill a congressman's children because of his stance on immigration.

Laurence Wayne Key allegedly called Brian Mast's Washington DC office and vowed to kill his young children Magnum, Maverick, and Madeline.

'I'm going to find the congressman's kids and kill them,' he told the intern who answered, according to police documents.

Laurence Wayne Key allegedly threatened to kill a congressman's children because of his stance on immigration

He allegedly called the Washington DC office of Florida Congressman Brian Mast (pictured) and vowed to kill his young children Magnum, Maverick, and Madeline

'If you're going to separate kids at the border, I'm going to kill his kids. Don't try to find me because you won't.'

The FBI arrested Key at his home in Stuart, Florida, soon after and charged him with communication of a threat to kidnap or injure a person.

He has called Congressman Mast's office 478 times and also contacted Senators Marco Rubio Bill Nelson the same day as he allegedly made the threats.

When interrogated he denied threatening to kill the three kids aged under eight, just that he should be separated from his children if he supported President Trump's immigration policies.

'I'm going to find the congressman's kids and kill them,' he told the intern who answered, according to police documents

He has called Congressman Mast's office 478 times and also contacted Senators Marco Rubio Bill Nelson the same day as he allegedly made the threats

This photo shows Key confronting Congressman Mast at an event in March

However, he 'did admit to saying something about Congressman Mast never seeing his kids again', the affidavit read.

Key is a vocal critic of Republican policy and regularly writes letters to politicians, some of which he published on social media.

He volunteers for the Democratic Party and Planned Parenthood and is often pictured at rallies, protests, marches, and meetings of political groups.

One photo showed him confronting Congressman Mast at an event in March and another at a March for Our Lives gun control rally.

The FBI arrested Key at his home in Stuart, Florida, soon after and charged him with communication of a threat to kidnap or injure a person

Key is a vocal critic of Republican policy and regularly writes letters to politicians, some of which he published on social media

Key's alleged phone call is the latest in a series of threats made to Republican politicians over President Trump's immigration policy.

They began after the policy of separating immigrant parents from their children after they crossed the U.S. border was publicized.

Congressman Mast was elected to Florida's 18th district at the last election after serving as a U.S. Army combat engineer in Afghanistan.

In 2010 he stepped on an IED and had both his legs and one of his fingers blown off. He now walks with prosthetic legs.