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(CNN) —  

Missouri Democratic Sen. Claire McCaskill said Thursday that Russians unsuccessfully attempted to hack her Senate computer network.

McCaskill’s acknowledgment was in response to a report from The Daily Beast that there was a phishing attempt against her office last year mirroring the tactics used successfully against John Podesta, Hillary Clinton’s campaign chairman in the 2016 presidential election. The US intelligence community has accused Russia of perpetrating the hack against Podesta and others in an effort to sway the election in favor of President Donald Trump.

“While this attack was not successful, it is outrageous that they think they can get away with this,” McCaskill said in a statement. “I will not be intimidated. I’ve said it before and I will say it again, (Russian President Vladimir) Putin is a thug and a bully.”

Thursday’s report said hackers sent forged emails to targets in the Senate with malicious links as part of an effort that Microsoft picked up. It said there was nothing to suggest the hacking attempt was successful.

CNN has rated the Missouri Senate contest a “toss-up,” as the Democratic senator seeks re-election in a state that went for Trump in 2016.

At the Aspen Security Forum last week, Microsoft corporate vice president for customer security and trust Tom Burt said Russia had attempted to hack into the online accounts of staffers on three congressional campaigns ahead of the midterm elections this year. The allegation from Microsoft in addition to The Daily Beast report marked the first major public accusations of attempted interference by Russia in the 2018 elections.

Top US national security officials have sounded the alarm about potential threats to the US in cyberspace. Director of National Intelligence Dan Coats said earlier this month that the situation was critical and went as far as comparing the “warning signs” to those faced ahead of the attacks on September 11, 2001.

“The warning signs are there,” Coats said. “The system is blinking. It is why I believe we are at a critical point.”