Senate Minority Leader Harry Reid (D-Nev.) speaks during the third day of the Democratic National Convention in Philadelphia, Wednesday, July 27, 2016. (AP Photo/J. Scott Applewhite)

Several leading Democratic lawmakers are asking the Federal Bureau of Investigation to investigate senior Trump campaign advisers for collusion in the suspected Russian hacking of American political organizations and election systems. It’s the most serious set of allegations to date about deep connections between the Trump team and the Kremlin, though the case is largely circumstantial.

On Monday, The New York Times broke the story of Senate Minority Leader Harry Reid’s August 27 letter to FBI Director James Comey asking the bureau to investigate alleged Russian interference in the U.S. presidential election, which followed new reports that foreign hackers penetrated two state election databases. In the same letter, without naming them directly, Reid pointed Comey to two specific Trump advisers, each of whom is allegedly connected to Russia, according to Reid and the Clinton campaign.

Reid’s letter implicitly asks Comey to look into the dealings of Roger Stone, the longtime Trump friend who has claimed to be in touch with Wikileaks founder Julian Assange, and Carter Page, a Trump foreign policy advisor who traveled to Moscow in July.

Stone, Assange and Russian state media have all been pushing a conspiracy theory that the hack of the Democratic National Committee was related to the shooting death of 27-year old DNC staffer Seth Rich. There’s no evidence the events are linked. Reid wants the FBI to investigate whether the similar statements are a coincidence or if they are all working together on the leaks.

“The prospect of individuals tied to Trump, Wikileaks and the Russian government coordinating to influence our election raises concerns of the utmost gravity and merits full examination,” Reid wrote, referring to Stone.

Reid also said the FBI should investigate if there were any “complicit intermediaries” between the Russian government and Assange, including “any United States citizen.”

On Tuesday afternoon, four leading House Democrats sent their own letter to Comey calling on him to investigate the Russian ties of Stone, Page, retired Lt. Gen. Michael Flynn, and former Trump campaign chairman Paul Manafort. “Serious questions have been raised about overt and covert actions by Trump campaign officials on behalf of Russian interests,” they wrote. “It is critical for the American public to know whether those actions may have directly caused or indirectly motivated attacks against Democratic institutions and our fundamental election process.”

In a statement, Clinton campaign spokesman Glen Caplin said the Trump campaign has multiple advisers with deep ties to Russia and the campaign doubled down on Reid’s call for an investigation into Roger Stone’s ties to Wikileaks and the DNC hacks.

“By admitting he’s in contact with Julian Assange through mutual friends, and claiming the Russian front Guccifer 2.0 is the source of hacked documents obtained by WikiLeaks, Roger Stone has raised serious and deeply troubling questions about potential collusion between Trump campaign associates and the Kremlin,” he said. “This alarming red flag is a question that demands answers.”

In an interview today, Stone lashed out at Reid’s call for the FBI to investigate. He said he has no connections with the Russian government and has communicated with Assange through a mutual friend only.

“He’s essentially accusing me of treason. It’s the new McCarthyism,” Stone said. “I have no connections with Russians at all. They call us the conspiracy theorists but they are the ones accusing us of treason.”

Stone said there’s no proof that the Russians did anything related to the DNC hacks because a hacker calling himself “Guccifer 2.0” claimed credit for the hack in June. But there is a growing consensus in the U.S. intelligence community that the DNC hack was orchestrated and perpetrated by the Russian government and forensic evidence suggests that “Guccifer 2.0” is a persona created by the Russian government hackers to try to cover their tracks.

Stone refused to characterize the frequency or nature of his indirect communications with Assange, but said he had no influence over Assange’s actions related to the leaks and was not directly coordinating with Wikileaks. But he called Assange a “freedom fighter” and a “hero” who was “fighting the deep state,” which means taking on the two-party duopoly in Washington.

In the interview, Stone also defended the Seth Rich conspiracy theory, accused Clinton or her allies of murdering at least three other people and said his email, bank, and social media accounts were all hacked last week by unknown assailants. Stone claimed that Assange has the “kryptonite” that will bring down the Clinton campaign, in the form of more leaked information about ties between the Clinton Foundation and the State Department during Clinton’s tenure as Secretary of State.

“I think he has the goods and he will release them at times of his choosing,” he said. “This makes me a conspiracy theorist? No, I’m a conspiracy realist.”

Reid also wrote to Comey that “questions have been raised” about whether a senior Trump adviser with investments in the Russian state energy firm Gazprom met with “high-ranking sanctioned individuals” during a July trip to Moscow. The passage clearly refers to Page, who gave a speech in Moscow in July at the graduation ceremony of the New Economic School that many observers viewed as a rebuttal of U.S. foreign policy.

“Washington and other Western capitals have impeded potential progress through their often hypocritical focus on ideas such as democratization, inequality, corruption and regime change,” Page said in the lecture.

Page declined to comment for this article but sources close to the issue told me Reid was briefed last week by a very senior U.S. intelligence official on the suspected Russian political interference and that Reid is particularly interested in Page’s activities while in Russia.

Reid and the Clinton campaign are steadily increasing their focus on the ties between Vladimir Putin and Donald Trump. In her speech last week on the “alt-right” movement, Clinton focused on the fact that the two men praise each other and she called Putin the “godfather” of a “global brand of extreme nationalism” to which Trump allegedly subscribes.

There’s definitely an overlapping of interests between the Trump camp and the Putin regime, not the least of which is a visceral hatred of Hillary Clinton. However, there’s very little actual hard evidence of real collusion.

Democrats and the Clinton camp are raising the stakes by calling on the FBI to investigate her political opponents for working with an enemy intelligence service. It’s another example of how both sides in this election cycle are pushing conspiracy theories that they cannot prove.