When Republican lawmakers this week abruptly canceled a plan to subpoena a former Ukrainian official in their investigations into the energy firm that hired former Vice President Joe Biden's son, they said it was to allow more time for senators to receive additional briefings.

But a Ukrainian magazine editor has told CNN that the target of the subpoena, Andrii Telizhenko, once offered him money to lobby U.S. senators on behalf of pro-Russian media outlets.

A former Ukrainian diplomat, Telizhenko is an ally of Trump's personal lawyer, Rudy Giuliani, and has been an enthusiastic proponent of the debunked theory that Ukraine, and not Russia, interfered in the 2016 U.S. elections. Telizhenko has also backed Republican claims that Trump's Democratic rival, Joe Biden, shut down an investigation into the Ukrainian gas company Burisma when his son, Hunter, served on its board. Biden has consistently denied any wrongdoing.

The Senate Homeland Security and Governmental Affairs Committee called off a vote to subpoena Telizhenko earlier this week, amid accusations from Democrats that the investigation was calculated to damage Biden's presidential bid.

Questions also swirled about Telizhenko's reliability as a witness – the FBI briefed staff on issues connected to the subpoena on Tuesday, the day before the committee was supposed to vote, according to a Senate Democratic aide. Telizhenko says he's the victim of a smear campaign and flatly denied to CNN he was a "Russian agent."

In a development that could raise more questions about Telizhenko's reliability, Vladislav Davidzon, who runs a magazine called the Odessa Review, has told CNN that Telizhenko offered him $5,000 in 2018 to approach prominent Republicans to speak out against efforts by Kyiv to curb the influence of two TV stations.

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CNN has reviewed a series of messages between the two men that came against the backdrop of an attempt by Ukrainian lawmakers to censure two channels, 112 UA and News One, for allegedly broadcasting Russian propaganda in the years following Moscow's annexation of Crimea in 2014.

In October 2018, the same month that lawmakers voted in favor of a resolution to sanction the two stations, Telizhenko wrote to Davidzon, asking: "Have a question do you or your father have contacts with U.S. Senators? I really need a favour for witch (sic) I can pay up to 5k."

Davidzon, 35, is the son of influential U.S.-based Russian language media owner Gregory Davidzon – once dubbed "The Kingmaker of Little Russia" in a 2012 profile by The New York Times.

After expressing concerns about how the new Ukrainian proposals could shut the broadcasters down, Telizhenko then says: "My question is is it possible to get an official comment on a Senators (Rand Paul, Lindsey Graham for example) website next week about this situation of censorship in Ukraine? Really important for me and need fast."

Davidzon replies: "Ok. I have a bit of time. But not sure what I can do."

Davidzon told CNN that he considered the offer of money to target senators like Graham was "improper" and never reached out to any U.S. lawmakers as a result.

In a telephone interview on Friday, Telizhenko said he had indeed contacted a small number of people including Davidzon on behalf of 112 and News One. He said the approaches were made on his own initiative and that the money he offered was his own, for expenses incurred.