Story highlights Julian Zelizer: Congress intended to be open institution, with members accessible to public

He says security has to be rethought after horrific shooting at GOP baseball practice

Julian Zelizer, a history and public affairs professor at Princeton University and a CNN political analyst, is the author of "The Fierce Urgency of Now: Lyndon Johnson, Congress, and the Battle for the Great Society." He's co-host of the "Politics & Polls" podcast. The opinions expressed in this commentary are his own.

(CNN) Wednesday's horrific shooting at a Republican congressional baseball practice in Virginia could have been even more devastating had the Capitol Police not acted in such heroic fashion.

This is not the first time there have been violent attacks against members of Congress, who historically receive far less protection than the president. The presence of Capitol Police on the scene apparently was due to the fact that one of those taking part, Rep. Steve Scalise, is the House majority whip and receives added protection as a member of the House leadership.

The fact that the alleged shooter was a Bernie Sanders volunteer and appears to have engaged in strong anti-Trump rhetoric in his social postings will inevitably generate conversations about whether partisanship has gone too far and we need to pull back.

Wasting no time, Rep. Steve King, an Iowa Republican, was quick to try to take partisan advantage of the situation by claiming that "the violence is appearing in the streets, and it's coming from the left." Of course to blame the left for such a deranged person would be to make the same mistake as blaming all conservatives for acts of violence by those on the right.

Although this story has rightly gripped the nation's attention and should be deplored, the reality is that violence against members of Congress has not generally changed the course of history.

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