Rep. Mike Lawler, R-N.Y., and Rep. Ritchie Torres, D-N.Y., plan to introduce a bipartisan bill that would provide "enhanced Secret Service protection" for President Joe Biden, former President Donald Trump and presidential candidate Robert F. Kennedy Jr.

"Last night's attempted assassination of former President Trump was a dark moment in our nation's history. As reports continue to emerge, it's clear that more protection is needed for all major candidates for president," Torres and Lawler said in a joint statement.

Investigators are still searching for any ties between the suspect and extremist organizations or individuals, scouring information from the suspect's phone and other digital devices, law enforcement sources said.

The shooter was identified by the FBI as Thomas Matthew Crooks, 20, of Bethel Park, Pennsylvania.

A 20-year-old Pennsylvania man was suspected to have been the gunman who attempted to assassinate former President Donald Trump on Saturday, firing several shots and killing at least one spectator, federal and local law enforcement agencies said.

The FBI early on Sunday identified the suspect, who was killed at the scene, as Thomas Matthew Crooks, of Bethel Park.

MORE | What we know about 20-year-old ID'd as suspected gunman

Wisconsin Republican Party Chair Brian Schimming said there are no changes, as of now, to the Republican National Convention, which begins Monday in Milwaukee, Wisconsin.

"I don't see a situation where there are massive changes. We haven't heard anything yet. We haven't been told anything that's going to change," Schimming said on "Upfront," a show aired on WISN-TV, an ABC affiliate station.

"Everything I've heard so far is we're still on track: vice presidential nomination on Wednesday night, of course, the presidential on Thursday," he said.

Milwaukee Police Department Chief Jeffrey Norman expressed confidence in security for the convention.

"This is a national special security event. There's no higher security that you can have for this type of event," Norman said. "It's important that we have that reassurance to our community, to those who are being participants, that we got this."

When asked whether Saturday's shooting prompted concerns about new protests, Norman said, "At this time, no, because we're all prepared, in regards to the engagement between our law enforcement partners and also our partners in the community. We're working out a lot of different plans."