Virginia Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, warned of potential "chaos" if foreign actors and governments successfully interfere in the 2020 elections, saying the U.S. was "lucky" the Russian government did not fully exploit vulnerabilities in U.S. election infrastructure in 2016.

"I think what the Russians did in 2016 was they were basically trying to jiggle the windows or try to open the doors and they found when they went into our voting systems that we were horribly unprotected," Warner said on "Face the Nation" Sunday.

"In many ways I think we were lucky that they didn't take advantage of some of the opportunities that we pointed out in our report. I don't think we can count on ourselves being lucky again in 2020," he added. "In many cases what a foreign government can do, they don't need to change vote totals. If they simply move thousands of people from one precinct to another, you would have chaos on Election Day."

Warner was referring to a report released on Thursday by his committee, one the few remaining bastions of bipartisanship in Congress. The heavily redacted report found that through its sprawling and sophisticated meddling campaign in 2016, Moscow targeted election infrastructure in all 50 states. In some states like Illinois, Russian hackers were in a position to alter or purge voter data.

The Virginia Democrat said the Department of Homeland Security — the main agency overseeing election security — has "upped its game" recently, but stressed that election systems in many states continue to be vulnerable to potential cyber intrusion by foreign actors and governments.

"What we're hearing from attorneys general and secretaries of states across the country is they need more help. What we're hearing is that there needs to be that paper ballot backup. Well, who could be against that?" Warner said.

He faulted President Trump and Republicans in Congress for blocking this week a broad election security legislative proposal spearheaded by Democrats.

"This administration has stopped every election security legislation from coming to the floor and they've been supportive in that effort by the Republican leader, Mitch McConnell," Warner said.