Washington (CNN) Congressional investigators have unearthed an email from a top Trump aide that referenced a previously unreported effort to arrange a meeting last year between Trump campaign officials and Russian President Vladimir Putin, according to sources with direct knowledge of the matter.

The aide, Rick Dearborn, who is now President Donald Trump's deputy chief of staff, sent a brief email to campaign officials last year relaying information about an individual who was seeking to connect top Trump officials with Putin, the sources said.

The person was only identified in the email as being from "WV," which one source said was a reference to West Virginia. It's unclear who the individual is, what he or she was seeking, or whether Dearborn even acted on the request. One source said that the individual was believed to have had political connections in West Virginia, but details about the request and who initiated it remain vague.

The same source said Dearborn in the email appeared skeptical of the requested meeting.

Sources said the email occurred in June 2016 around the time of the recently revealed Trump Tower meeting where Russians with Kremlin ties met with the president's eldest son, Donald Trump Jr., his son-in-law Jared Kushner as well as then-campaign chairman, Paul Manafort.

While many details around the Dearborn email are unclear, its existence suggests the Russians may have been looking for another entry point into the Trump campaign to see if there were any willing partners as part of their effort to discredit -- and ultimately defeat -- Hillary Clinton.

Dearborn's name has not been mentioned much as part of the Russia probe. But he served as then-Sen. Jeff Sessions' chief of staff, as well as a top policy aide on the campaign. And investigators have questions about whether he played a role in potentially arranging two meetings that occurred between the then-Russia ambassador to the US, Sergey Kislyak, and Sessions, who has downplayed the significance of those encounters.

Dearborn was involved in helping to arrange an April 2016 event at the Mayflower Hotel where Trump delivered a major foreign policy address, sources said. Kislyak attended the event and a reception beforehand, but it's unclear whether he interacted with Sessions there.

Dearborn did not respond to multiple inquiries seeking comment. White House Press Secretary Sarah Huckabee Sanders declined to comment, and would not respond to inquiries about Dearborn's email and whether the campaign carried through with that meeting.

"We aren't going to comment on potentially leaked documents," Sanders said.

Intelligence experts say the request made by the unidentified West Virginian fits a pattern of Russians trying to gather human intelligence and seek unwilling -- and sometimes unwitting partners -- as part of their covert operations.

"The Russians are really experts at this," said Steve Hall, a retired CIA chief of Russia operations.

But Hall added that it would be unusual to set up a meeting with Putin himself before meeting with operatives tied to the Kremlin.

Emails about potentially meeting Putin

The Russian "active measures" campaign to influence the US election was fully underway when Dearborn sent his email. This included cyberattacks against the Democratic National Committee and Clinton's senior staffers, as well as pro-Trump messaging by Kremlin-backed propaganda outlets, according to a report declassified by the US intelligence community in January.

And Dearborn wasn't the only person within the Trump campaign emailing about potential Russia meetings. Trump campaign adviser George Papadopoulos sent an email to top campaign officials in March 2016 about arranging meetings with Russians, sources said. The subject line was "Meeting with Russian Leadership -- Including Putin," according to the source.

Sources told CNN that senior campaign officials dismissed that proposal. Papadopoulos has not responded to CNN's previous requests for comment.

Despite the fact that his idea was brushed aside, Papadopoulos continued his emails about arranging meetings with Russians to other Trump campaign officials for months, The Washington Post reported

"Putin wants to host the Trump team when the time is right," Papadopoulos wrote in an email on April 27 to then-campaign manager Corey Lewandowski, according to the Post. On that same day, Trump delivered his foreign policy speech at the Mayflower Hotel.

The emails from Dearborn and Papadopoulos were included in the batch of 20,000 emails that the Trump campaign handed over to multiple congressional committees earlier this summer.

CNN has reported that the FBI saw intelligence last summer suggesting that Russian operatives tried to use Trump advisers to infiltrate the campaign. Sources said this intelligence referenced foreign policy adviser Carter Page. Page denies ever working for Russia or having any improper contact with Russians.

Sessions led the campaign's foreign policy team, which included Page and Papadopoulos.

Undisclosed meetings with Kislyak

Sessions met at least twice during the campaign with Kislyak, and congressional investigators want to question whether Dearborn was involved in arranging those meetings, which took place in July and September 2016, sources said.

The Attorney General first acknowledged the meetings in March, despite testifying at his confirmation hearing that he "did not have communications with the Russians" and repeated denials from Trump officials that there were any contacts between the campaign and Russians.

The kerfuffle over Sessions' meetings and his lack of disclosure helped trigger his recusal from overseeing the Russia investigation, an action that was widely praised but angered Trump.

CNN reported in May that congressional investigators were examining whether Sessions attended a third private meeting with Kislyak, at the Mayflower event that Dearborn apparently helped plan.

Sessions later told the Senate intelligence committee he didn't remember meeting with or talking to Kislyak at the hotel. Kushner also helped organized the event, and he told congressional investigators earlier this summer that he briefly "shook hands" and "exchanged brief pleasantries" with Kislyak at a reception before Trump's speech.

During the speech, Trump said that "an easing of tensions and improved relations with Russia, from a position of strength, is possible." Kislyak watched from his seat in the front row.

Sessions ally lands in the White House

Dearborn spent nearly two decades working for Sessions in the Senate, eventually rising to chief of staff, a position he held for 12 years, including throughout the 2016 campaign.

Like his boss, who was a top Trump surrogate on the presidential campaign trail, Dearborn played dual roles last year. He ran Sessions' Senate office and also led the Trump campaign's Virginia-based policy shop, handling congressional relations and crafting policy proposals.

The Trump campaign paid Dearborn more than $28,000 last year, mostly for "policy consulting" but also to reimburse travel expenses, according to Federal Election Commission filings.

Shortly after Trump's victory, Dearborn emerged as executive director of the Trump transition.

Dearborn was later appointed Trump's deputy chief of staff for legislative, intergovernmental affairs and implementation, cementing his position in the White House as a senior policy aide. He is among the handful of Sessions aides who landed plum jobs in the administration.