Security researchers have found 35 backend election systems in 10 states that have connected to the internet at some point in the past year, putting them at risk of being hacked or tampered with, as first reported by Motherboard.

The researchers also found that the election systems are behind firewalls that could be misconfigured or otherwise insecure.

The systems are made by Election Systems & Software, the top voting machine company in the United States.

ES told Motherboard that the systems don’t connect to the “public internet,” a claim the company had made prior to the research.

But a number of the sites named by researchers were pulled offline shortly after the findings were disclosed, suggesting the researchers’ conclusions are valid.

These aren’t the first concerns over ES’s security practices: in 2018, the company disclosed that it installed remote-access software on some voting machines from 2000 to 2006.

After Twitter temporarily locked the campaign account of Senate Majority Leader Mitch McConnell, a string of leading Republican campaign committees announced an ad spending boycott against the social media platform.

McConnell's official campaign account was locked Wednesday after his team posted a video of protesters outside his Louisville, Kentucky, home earlier this week.

Twitter's blanket policy bans videos that include violent threats, even from those who receive such threats.

The video in question, which also aired on Fox News, featured protest chants calling McConnell "murder turtle," and shouts from the crowd inciting violence against him.

Twitter told CNET in a statement that McConnell's campaign account was locked because the video "violated our violent threats policy, specifically threats involving physical safety."

"I have directed the @nrcc to immediately halt all spending with @Twitter until they correct their inexcusable targeting of @Team_Mitch.

For two years in a row, hackers at Defcon have demonstrated that voting machines currently being used in US elections had serious security issues.

Now with the 2020 US presidential election quickly approaching, lawmakers who want to fix those vulnerabilities are heading to the hacking conference in Las Vegas to see them in person.

While there's no evidence that any votes were tampered with during the 2016 election, hackers have shown plenty of proof that the voting machines being used are vulnerable to attacks.

Lawmakers like Sen. Ron Wyden, a Democrat from Oregon, have proposed legislation to improve election security to make sure these vulnerabilities wouldn't affect future voters.

"White hat hackers do an invaluable public service in this technologic age by identifying security holes and, if necessary, shaming the government or the companies responsible into fixing them," Wyden said in a statement.

This comes after former special counsel Robert Mueller warned Congress last month that Russia would continue its efforts to hack US elections, telling lawmakers, "They're doing it as we sit here."

Major Republican committees and President Donald Trump’s reelection campaign are pulling all advertising money from Twitter as of Thursday morning after the platform locked Senate Majority Leader Mitch McConnell’s (R-KY) campaign account for violating the platform’s rules.

Trump’s campaign, the National Republican Senatorial Committee (NRSC), and the National Republican Congressional Committee (NRCC) are promising to not spend any money on future Twitter campaign ads.

Richard Waters, the chief of staff of the Republican National Committee (RNC), said in a tweet that his organization, along with the Trump campaign, will not advertise on Twitter until “they address this disgusting bias.”

I have directed the @nrcc to immediately halt all spending with @Twitter until they correct their inexcusable targeting of @Team_Mitch.

We will stand firmly with our friends against anti-conservative bias.

— Parker Hamilton Poling (@parkerpoling) August 8, 2019