WASHINGTON — A Senate vote to end President Donald Trump’s impeachment proceedings without calling witnesses should be considered “half a trial,” the president’s former chief of staff John Kelly said Friday.

“In my view, they kind of leave themselves open to a lot of criticism,” Kelly said in an interview with NJ Advance Media in advance of his Feb. 12 appearance at Drew University’s Drew Forum speaker series at the Mayo Performing Arts Center in Morristown.

“It seems it was half a trial,” Kelly said.

Kelly said he believed former National Security Adviser John Bolton’s assertion that Trump withheld congressionally approved aid to Ukraine to pressure that government into investigating former Vice President Joe Biden, a leading candidate for the 2020 Democratic presidential nomination.

Bolton, who made the claims in an unpublished book reported by the New York Times, was “a copious note taker” and was “an honest guy and an honorable guy,” Kelly said.

Kelly, whose wife Karen grew up in Teaneck, made his comments just hours before the Senate’s planned vote Friday on whether to call witnesses in its trial of the president.

Trump refused to allow his aides to testify and refused to turn over documents to the House, which last month made him only the third president ever to be impeached.

Three-quarters of U.S. voters in a Quinnipiac University poll released this week supported calling witnesses in the Senate trial, with just 20 percent opposed.

“If I was advising the United States Senate, I would say, 'If you don’t respond to 75 percent of the American voters and have witnesses, it’s a job only half done,” he said. “You open yourself up forever as a Senate that shirks its responsibilities.”

Kelly is a retired Marine Corps general who served as Trump’s secretary of homeland security before becoming White House chief of staff from July 2017 to the end of 2018.

Once the impeachment trial ends, Kelly said, Trump should invite the congressional leaders of both parties to the White House and move ahead on issues such as infrastructure.

“If I was there, I’d recommend the president have leadership over and say, ‘OK, now that this is behind us, let’s talk,’” Kelly said. “We can maybe take a breath over the weekend and make a commitment to each other. It would be such a wonderful outreach.”

But with the next presidential election just 10 months away, “it’s unlikely to happen,” he said.

The assertions about withholding aid led several Democrats who were on the fence on impeachment to support an inquiry. After seven rookie Democrats with military or intelligence backgrounds, including Rep. Mikie Sherrill, D-11th Dist., endorsed an inquiry, House Speaker Nancy Pelosi, D-Calif., moved ahead with hearings.

In December, the House voted largely along party lines to impeach the president. Only two Democrats, including New Jersey Rep. Jeff Van Drew, voted against both articles.

Van Drew then switched to the Republican Party, and was endorsed for re-election by Trump at a campaign rally in Wildwood on Tuesday.

U.S. Sen. Cory Booker, D-N.J., answering questions on Facebook Live on Wednesday, said that not only was acquittal a foregone conclusion, but senators would not take any other action either, such as working to block foreign intervention in American elections.

“I’m not optimistic that we have the votes in the Senate to any kind of corrective action,” Booker said. “Remember what he has been impeached for is conduct that is threatening to our very democratic processes. That’s the threat and the worry we have.”

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter at @JDSalant or on Facebook. Find NJ.com Politics on Facebook.

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