U.S. Sens. Susan Collins and Angus King Credit: Andrew Harnik / AP

The United States must do more to combat Russia’s influence on this year’s election, Maine’s two U.S. senators said Tuesday in response to the release of the fifth and final volume from the Senate Intelligence Committee’s investigation into Russian election meddling.

Independent U.S. Sen. Angus King, who usually caucuses with Democrats, slammed President Donald Trump’s 2016 election effort for opening “the door to a devastating Russian active measures operation,” while Republican U.S. Sen. Susan Collins, who faces an uphill election fight against Democratic challenger Sara Gideon, named bills she has co-sponsored that aim to bolster election security.

The 966-page document is touted as the most comprehensive examination yet of Russian state-sponsored interference with the last presidential election, and represents a rare bipartisan consensus on a hotly contested topic. Collins and King serve on the committee, which conducted more than three years of investigative activity, more than 200 witness interviews and reviewed more than a million pages of documents.

The president and his inner circle made themselves prime counterintelligence targets for Russian intelligence operatives by doing business and working with Russian oligarchs — and they are still vulnerable to Russian influence, said King, who called the report “a wake-up call for all Americans.”

“Rather than disavowing this threat, President Trump and his inner circle have denied the unambiguous facts laid out in the report and, inexplicably, continue to take actions that support the aims and ambitions of Vladimir Putin,” King said. “The fact is that the findings of the committee — supported on a bipartisan basis — matter more at this moment in time than ever before,”

Collins touted her efforts to improve U.S. election security. She cited her co-sponsorship of the Foreign Influence Reporting Elections Act, the Defending Elections from Threats by Establishing Redlines Act, and the Secure Election Act and her advocacy of spending an additional $425 million in election security funding this year.

“I believe all five volumes, but especially Volume 5, will serve for our government and historians as a critical, fact-based account of the events surrounding the 2016 election,” Collins said.

The Associated Press contributed to this report.