Sen. Chris Murphy (D-Conn.) criticized former Vice President Mike Pence’s proposal to give arrested mass shooters the death penalty, saying the remarks show his ignorance on the topic.

The proposal “shows how little Mike Pence understands about the gun violence epidemic in this country,” Murphy said in a CBS interview on Tuesday.

“Fact is, most mass shooters are engaged in a suicide attempt,” he continued. “Mike Pence doesn’t know what he’s talking about when he says that he thinks mass shootings will go down if you threaten to kill the people who are carrying them out. They are, in fact, seeking to die.”

Murphy is one of the Senate’s most vocal gun control advocates. He has also led bipartisan attempts to pass gun control legislation in the Senate.

He said that aims to curb mass shootings should not be focused on punishment, but on prevention. 

“The most important thing we can do now is make sure those mass shooters can’t have access to military weapons,” he said. “If you really want to do something about these mass shootings, then we need to get these weapons of mass destruction — the AR-15s, the semi-[automatic], assault-style weapons out of the hands of these killers.”

With the exception of the bipartisan gun safety bill passed last year — which Murphy was a lead negotiator on — few gun control measures have passed Congress in recent years. That measure saw 15 Republicans in the Senate join all Democrats.

The law expanded criminal background checks, closed straw purchase loopholes, provided funding to states for gun safety programs and funded mental health services.

Murphy said bipartisanship like that could not have happened five years ago and is likely to continue going forward.

“The Republican Party is in the midst of a change,” he said.

“I think you’ll see more Republicans … support changes to our gun laws, because they really aren’t interested in running in a general election where the general electorate is so firmly decided,” he continued. “The general electorate wants universal background checks and an assault weapons ban. I think that’s going to become more and more clear to Republicans who are running.”