Calling witnesses — including former national security adviser John Bolton — to President Donald Trump’s impeachment trial is likely to cause short-term volatility in financial markets, warns Tom Elliott, international investment strategist at deVere Group.

The impeachment trial of Trump is nearing a pivotal vote on whether to hear from witnesses requested by Senate Democrats arguing for his removal from office.

Whatever happens, Trump is unlikely to be removed because his Republican Party has a 53-47 majority in the Senate, and a two-thirds majority of the chamber is needed to remove a president. A decision to hear from witnesses would require only four Republicans to cross party lines, however, Reuters reported.

A decision to hear from witnesses would drag out the trial and potentially undermine a key leg of Trump's defense - that much of the Democrats' case against him is based on hearsay.

One witness sought by Democrats — Bolton — says in a new but as-yet unpublished book that Trump told him that a freeze on aide to Ukraine was linked to his push for the country to investigate former Vice President Joe Biden and his son, Hunter Biden, according to a New York Times report.

With an eye on Trump’s bid for a second term in the presidential election in November, many Republicans in the Senate have been pushing for a speedy trial without witness testimony.

Democrats argue that without witnesses there cannot be a proper trial. Republicans counter that Democrats should have called the witnesses during the impeachment inquiry in the House of Representatives. The White House had told officials not to cooperate in that inquiry.

“It was assumed that Trump’s impeachment trial would be done and dusted this week," Elliott said.

“Financial markets don’t want a drawn-out impeachment trial. They want certainty, especially as investors are already nervous because of the coronavirus outbreak," he said.

“The longer the process, the more volatility will occur in global financial markets," he said.

“Some sectors are more at risk of a longer impeachment trial — and damage to President Trump — than others," he said. 

“Sectors that would suffer from regulation by Democrats, notably pharma, energy and banks want him to win again," he said. “Expect banks, pharma and energy to lead this market volatility if Bolton is called by the Senate.”

Meanwhile, Trump has said he would use a legal doctrine called executive privilege to block or limit Bolton's testimony, Reuters explained.

Executive privilege, in certain situations, allows a president to keep private the nature of conversations with aides. The doctrine is rooted in the idea that a president governs more effectively if aides can speak candidly.

Legal experts say that Chief Justice John Roberts, who is presiding over the trial, or the senators themselves, would rule on any claim by Trump that his conversations with Bolton are protected by executive privilege.

Trump could also file a lawsuit seeking a court order that would limit Bolton's testimony.

Some legal experts argue that Trump’s executive privilege claim would be weak, saying Congress' interest in hearing from Bolton would outweigh Trump's desire for secrecy.