DAVOS, Switzerland (Reuters) - U.S. President Donald Trump on Wednesday said he would prefer a longer impeachment trial so that current and former top administration officials could testify, but that having them appear would present national security concerns.

Trump, speaking to reporters as he prepared to leave the World Economic Forum in Davos, Switzerland, also said he would love to go appear at the Senate trial in his own defense but that his lawyers would likely object.

"I'd love to go," he said during a roughly 40-minute-long news conference. "I'd love to do it."

The Republican president said it was up to the Senate to decide how to handle the trial, but that he would like to have former national security adviser John Bolton and U.S. Secretary of State Mike Pompeo testify.

"The problem with John (Bolton) is that it's a national security problem," Trump said before returning to Washington, where opening arguments were set to begin in the historic proceedings.

"He knows some of my thoughts, he knows what I think about leaders. What happens if he reveals what I think about a certain leader and it's not very positive?" he said, adding that Pompeo testifying would also be a risk.

"You could call it presidential prerogative," Trump said. "The way I look at it, I call it national security, for national security reasons. Executive privilege."

Senators must decide whether to remove Trump from office after he was impeached last month by the Democratic-controlled House of Representatives on charges of abuse of power and obstruction of Congress for pressuring Ukraine to investigate former Democratic Vice President Joe Biden, a political rival, and impeding the inquiry into the matter.

Trump also said he would want to have his acting chief of staff Mick Mulvaney testify but that he would not have much more to add to his public comments in television interviews. He also said he would want Rick Perry, adding that the former U.S. Energy Secretary had asked him if he could testify.

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"I would rather go the long way," he said.

But, he added, "I'll leave that to the Senate," adding that he would watch the proceedings after leaving the summit.

Trump also said that he would like to have his personal lawyer Rudy Giuliani, whose efforts on behalf of the president in Ukraine are at the center of the impeachment, serve on his legal team in the Senate but that there could be a conflict.

"He could be a witness at some point," he said.





(Reporting by Alexandra Alper; writing by Susan Heavey; Editing by Andrew Heavens and Chizu Nomiyama)