Lindsay Hoyle has declared “we are at war” in the wake of the assassination attempt on Donald Trump.
The Commons Speaker described the shooting as “another attack on democracy”.
Trump, the Republican Party nominee to be the next US president, narrowly escaped with his life following the attack at a campaign rally on Saturday.
The suspected shooter, 20-year-old Thomas Crooks, was shot dead at the scene.
Speaking to Times Radio on Monday, Hoyle said: “This is another attack on democracy. This is trying to see people influence the democratic process.
“Because they don’t believe in the ballot box, they go to extreme measures, which is my biggest worry about the future of democracy. We’ve got to protect democracy. We’ve got to protect the candidates who put themselves forward.
“And the first thing I wanted to do was express my worries and concerns in sending a letter to the former President, also to the Speaker as well, to say, look, we are at war. We believe in the democratic process. We must never give in to the others who don’t believe in our values.”
With the State Opening of Parliament taking place on Wednesday, Hoyle said security officials are always looking at ways to ensure the safety of politicians.
He said: “Security measures are looked at all the time. There is a lot more than what you see. I never discuss the security measures that we do have. I’m always happy to talk in general terms and we’re always looking. We don’t stand still because we think we’ve got it right. That would be the wrong thing.”