Washington (CNN) One of the Russians who was in touch with Trump campaign aide George Papadopoulos throughout 2016 told CNN he was willing to open doors for the campaign, and broker meetings with Russian officials, only to see the "unprofessional" young aide disappear from his radar.

The comments from Russian foreign policy analyst Ivan Timofeev, shed new light on how Papadopoulos repeatedly tried but failed to arrange a Russia trip for himself or other aides working for President Donald Trump's campaign.

"We did not close the door to the guy, but we did not take it seriously," Timofeev told CNN earlier this year in his Moscow office. "He was very enthusiastic. He was very interested in Russia and improving relations, but he seemed to be so unprofessional and so unprepared for a serious conversation."

Those efforts, futile as they may be, stayed relevant well beyond 2016.

Timofeev was stopped at a US airport last year and questioned by investigators working for special counsel Robert Mueller, according to two sources familiar with the matter. Papadopoulos lied to the FBI about his contact with Timofeev and others. He pleaded guilty in October to making false statements and is now cooperating with Mueller as he awaits sentencing later this year.

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