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Democratic Sen. Sheldon Whitehouse this week said he was sure the Russia-related cloud hanging over President Donald Trump's administration would not be clearing up anytime soon.

And he said Republicans were beginning to take the accusations much more seriously.

Whitehouse, who is the ranking member on the Senate Judiciary subcommittee investigating Russia's role in the 2016 election, spoke with Business Insider this week while promoting his newly released book, "Captured: The Corporate Infiltration of American Democracy."

The Rhode Island Democrat said the investigation from the Subcommittee on Crime and Terrorism, which is chaired by Republican Sen. Lindsey Graham of South Carolina, would first explore the "toolbox that Russia uses in our elections and in other elections to try to engage in election manipulation."

The subcommittee will then evaluate the legality of what took place during the election. Several US intelligence agencies concluded that Russia meddled in the election process to assist Trump and harm the Democratic nominee, Hillary Clinton.

Whitehouse said the subcommittee investigation would consist of "three big buckets."

"Russia's importance to Trump's business enterprises and what influence that may have over his conduct, traditional old-fashioned kompromat, and then engagement between his campaign and the Russians around the torquing of the election away from Hillary," he said. "It's one thing if they torqued the election away from Hillary and gave it to him — it's another if they were conspiring with each other or planning with each other. The first is bad, the second is ... worse."

Recent reports have indicated that several Trump associates were in constant communication with Russian officials during the presidential campaign. Trump has denied any knowledge of such contact. Additionally, Michael Flynn resigned as national security adviser last week after multiple outlets reported he discussed sanctions with a Russian ambassador before Trump took office and then was not forthright about the content of his communications with Vice President Mike Pence.

Trump has attempted to downplay the stories related to Russia, saying during a press conference last week that "Russia is fake news."

Many of these reports, Whitehouse said, have led his Republican colleagues to become increasingly concerned about Trump's alleged ties to Russia.

"The private conversation around the Senate is that, very much, this is serious," he said. "The experienced Washington reporters that you talk to are all digging. And many of them are very optimistic about being able to find significant things. Somebody in politics can tell when the dogs are hunting, and when they're just running around. And these dogs are hunting. They're making game. They're on their business."

He added that intelligence officials and law enforcement had made it clear "this is a long way from over."

"So I think that helps," he said. "And then I think they wouldn't put it past Trump to do any of this stuff for a second."

"I think it's all converging to a point where people are collectively holding their breath and we will see what is the next shoe to drop," he continued. "My personal observation is that there is very little good will for this man with Republicans in the Senate."

But senators do not want to cross Trump's loyal voters, Whitehouse said, adding that the appearance of going after him too soon would be politically costly for his GOP colleagues.

"But, if something comes out that changes that dynamic, if the switch flips, the elevator goes straight to the basement," he said. "There's very little in terms of arms reaching out to help him."