BANGOR (NEWS CENTER Maine) — After a threatening letter claiming to contain ricin was sent to Sen. Susan Collins' Bangor home, her husband is speaking out saying he is concerned for his wife's safety.

“She’s been subject to a lot of threats, and obviously it’s scary...I’m obviously very concerned about Susan...I’ve never seen anything like this,” said Collins' husband, Thomas Daffron.

RELATED | Letter delivered to Sen. Collins' Bangor home claimed to contain ricin

According to Sen. Collins' spokesperson, Daffron received the threatening letter Monday afternoon at his and Collins' West Broadway home. Daffron, the couple's dog and parts of the home were quarantined while crews subsequently worked to analyze the premises and affected areas.

VIDEO | Sen. Collins' husband Thomas Daffron says he's scared for his wife's safety

“If we don’t do something to restore civility in this process, it’s going to be very difficult for this country to function,” Daffron told NEWS CENTER Maine outside his Bangor home Tuesday morning.

Daffron told NECN's Danielle Waugh the letter claiming to contain ricin was addressed to him.

The couple, who have been married since 2012, received many invitations from people offering to take them in, Daffron said, but they ultimately chose to stay in their Bangor home Monday night after experts cleared the residence of any danger.

PHOTOS | Crime tape outside Sen. Collins' Bangor home

Testing of the letter and an investigation into its origins is now being headed up by the Federal Bureau of Investigation.

Daffron, who is a former newspaper reporter and worked for decades in political circles as a top staffer for U.S. Senators, says you can't live in fear, despite the many threats directed at his wife.

"I have never really seen anything like this, and I started in the Senate in the early 1970s, and I am obviously very concerned about Susan."

Daffron says there have been many contentious votes throughout the years but nothing like what is happening in today's political climate.

"We've had...protestors in front of our house for several weeks and I think that makes life a little more complicated and makes it more difficult for [Susan] to do her job," Daffron said while acknowledging that people have a right to protest in public locations.

Ricin is a highly hazardous poison derived from the husks of castor beans, which are the seeds from the castor oil plant. It has been used in previous attacks against the U.S. Senate, President Barack Obama and then-New York Mayor Michael Bloomberg.

"We are very grateful for the immediate and professional assistance that we received from the Bangor Police Department, the Maine Crime Lab, the Maine State Police Department, the Capitol Police, the FBI, the Orono Hazmat Unit, the Bangor Fire Department, the U.S. Army, and the U.S. Postal Inspection Service," Collins and Daffron said in a joint statement. "We are also truly appreciative of the many well wishes that we received today. Our friends and neighbors have been incredibly kind and have even offered to open their homes to us. We feel blessed to live in such a supportive community."

Collins' staff said the Senator plans to be in Maine for the duration of this week.