MADISON - U.S. Sen. Ron Johnson discussed a conspiracy theory about Ukrainian involvement in the 2016 election with a Ukrainian diplomat this summer, further drawing the Republican from Oshkosh into issues at the heart of the impeachment inquiry of President Donald Trump.

The Washington Post reported Monday that Johnson met with Ukrainian diplomat Andrii Telizhenko for at least 30 minutes in July. Telizhenko told the newspaper he talked to Johnson about an unsubstantiated claim that Ukraine interfered in the 2016 election and that in addition to his conversation with Johnson he met with Senate staff for about five hours.

Already Johnson has held a key role in diplomacy with Ukraine. House Democrats are investigating whether Trump put inappropriate pressure on Ukrainian officials by holding up nearly $400 million in aid while asking them to launch investigations into the 2016 election and former Vice President Joe Biden and his son Hunter, who served on the board of a Ukrainian gas company.

According to Telizhenko, Johnson's aides initiated the contact between the two.

"I was in Washington, and Sen. Johnson found out I was in D.C., and staff called me and wanted to do a meeting with me. So I reached out back and said, ‘Sure, I’ll come down the Hill and talk to you,' " Telizhenko told the newspaper.

The two appear in a Facebook photo Telizhenko posted on July 11. That's two weeks before Trump told Ukraine President Volodymyr Zelensky he wanted him to do a "favor" and investigate Biden, one of the leading Democrats challenging him in next year's election.

Johnson and his aides have repeatedly declined to answer questions from the Milwaukee Journal Sentinel for more than two weeks.

He has declined to say whether he believes he could participate in proceedings in the Senate if the House votes to impeach Trump. Two ethics experts told the Journal Sentinel this month that Johnson should consider recusing himself from a vote on removing Trump because of Johnson's involvement in the matter.

Johnson's name has come up in key closed-door testimony over impeachment.

'Irregular channel' on Ukraine

Johnson attended a May 23 Oval Office meeting where an “irregular channel began” for U.S. foreign policy with Ukraine, diplomat William Taylor testified last week.

At that meeting, Trump directed those in the meeting to talk to his personal attorney, Rudy Giuliani, about his concerns with Ukraine, according to testimony this month from Gordon Sondland, the U.S. ambassador to the European Union.

“It was apparent to all of us that the key to changing the president's mind on Ukraine was Mr. Giuliani,” Sondland said in his testimony.

Johnson told the Washington Post he did not recall Trump mentioning Giuliani at the meeting.

In an appearance last week on Fox News, Johnson told host Mark Levin he and the others at the meeting urged Trump to invite Zelensky to the White House and appoint an ambassador to Ukraine that could get bipartisan support.

“I was certainly surprised by the president’s reaction, which has been consistent throughout this,” Johnson said. “First of all, he talked about the level of corruption in Ukraine. And, Mark, there’s all kinds of smoke about Hillary Clinton's campaign, the DNC being involved in the 2016 election.”

Johnson was referring to an unsubstantiated conspiracy theory some conservatives have latched onto that Ukraine has the Democratic National Committee's servers or was involved in planting the idea that Trump’s campaign worked with Russia in the 2016 election.

Johnson, the chairman of the Senate’s Homeland Security Committee, has long been involved in Ukraine policy:

May 20. Johnson attended Zelensky’s inauguration as part of a delegation that also included Sondland; Kurt Volker, the U.S. envoy for Ukraine; and Rick Perry, the energy secretary.

During that trip, Volker told the others about news reports of Giuliani’s calls for investigations into Ukraine, including Biden, according to the Wall Street Journal. The group was surprised about Giuliani’s activities, according to the report, which was based on an unnamed source familiar with the trip.

Johnson has not responded to questions from the Journal Sentinel since the Wall Street Journal published its report.

May 23. Johnson and the others from the delegation encouraged Trump to back Zelensky. Trump raised concerns about corruption and, according to Sondland and others, directed them to work with Giuliani.

In his testimony last week, Taylor said he was handling Ukraine policy through the regular channel, but he learned there was a second, irregular channel as well.

"This irregular channel began when Ambassador Volker, Ambassador Sondland, Secretary Perry, and Senator Ron Johnson briefed President Trump on May 23 upon their return from President Zelensky’s inauguration," he testified.

The delegation supported Zelensky but "Trump did not share their enthusiasm for a meeting with Mr. Zelensky," Taylor testified.

Around July 11. Johnson met with Telizhenko and discussed the DNC conspiracy theory, according to the Washington Post.

Just after the Post published its story, Telizhenko renewed his questions about the 2016 election, called Johnson "high ranking" and said his committee has a "duty to investigate any claims."

July 18. Taylor said he learned Trump had put a hold on nearly $400 million in aid to Ukraine that had been approved by Congress.

July 25. Trump asked Zelensky in a phone call to do him a “favor” and investigate the 2016 election and the Bidens.

Trump's call with Zelensky triggered a whistleblower's complaint and, later, the impeachment inquiry. Johnson has said he considered Trump's call to Zelensky gracious and a sign that Trump wanted to get to the truth.

Aug. 30. Sondland told Johnson the aid would go to Ukraine after the country appointed a prosecutor to investigate the 2016 election, according to Johnson. Johnson told the Wall Street Journal he “winced” at the notion the aid would be linked to an investigation.

“I can’t tell you exactly how Gordon described this but there was something in the works, they were trying to do something, President Zelensky would have to do something in order to really free up that support,” Johnson said on Levin’s show.

Aug. 31. Johnson spoke to Trump and asked him whether the aid was tied to an investigation. Trump denied it, and Johnson took him at his word.

“I then brought up this rumor I’d heard, is there something in the works, is there, I mean, does Zelensky have to do something or does Ukraine show you something in order for this support to be released?” Johnson told Levin. “And that is where he made the adamant, vehement, angry denial. I described it as expletive deleted. ‘No way, no, no, I would never. Who told you that?’ At which point I felt a little guilty. ‘Well, it was Gordon.’”

In that conversation, Johnson also asked Trump to give him the authority to tell Zelensky that the U.S. aid was coming. Trump wouldn’t give him that power but told him he thought Johnson would like the decision he would eventually make on the Ukraine aid, according to Johnson.

Sept. 5. Johnson and Democratic Sen. Chris Murphy of Connecticut met with Zelensky in Ukraine and told him his country has bipartisan support in Congress.

Johnson has said Zelensky gave no indication he felt pressured. Murphy has said Ukranian officials were concerned about ignoring Giuliani’s requests for investigations.

Sep. 11. The Trump administration released the Ukraine aid that had been upheld since July.

While Johnson has said Trump denied there was any quid pro quo, he has also said Trump specifically cited concerns about the 2016 election during their discussions.

“Unlike the narrative of the press that President Trump wants to dig up dirt on his 2020 opponent, what he wants is he wants to — an accounting of what happened in 2016,” Johnson said in a combative Oct. 6 appearance on NBC’s “Meet the Press” “Who set him up? Did things spring from Ukraine?”

“The president told me repeatedly in the May 23rd Oval Office visit, on the phone on the 31st (of August), the reason he had very legitimate concerns and reservations about Ukraine is first, corruption, generalized. And then specifically about what kind of interference (there was) in the 2016 election.”

As he put it in a stop in Sheboygan last month: “The president was very consistent about why he was considering it. Again, it was corruption — overall, generalized, no doubt about it. What happened in 2016? What happened in 2016? What was the truth about that?”

Contact Patrick Marley at patrick.marley@jrn.com. Follow him on Twitter at @patrickdmarley.