WASHINGTON — House Democrats are refining part of their impeachment case against the president to a simple allegation: Bribery.

House Speaker Nancy Pelosi on Thursday brushed aside the Latin phrase “quid pro quo” that Democrats have been using to describe President Donald Trump’s actions toward Ukraine. As the impeachment hearings go public, they’re going for a more colloquial term that may resonate with more Americans.

“Quid pro quo: Bribery,” Pelosi said about Trump’s July 25 phone call in which he asked Ukrainian President Volodymyr Zelenskiy for a favor.

Trump says the call was perfect. Pelosi said: “It’s perfectly wrong. It’s bribery.”

The House has opened its historic hearings to remove America’s 45th president, with more to come Friday, launching a political battle for public opinion that will further test the nation in one of the most polarizing eras of modern times.

Democrats and Republicans are hardening their messages to voters, who are deeply entrenched in two camps.

Trump continued to assail the proceedings as “a hoax” on Thursday, and House GOP Leader Kevin McCarthy dismissed the witness testimony as hearsay, at best second-hand information.

The president, who said he was too busy to watch the initial hearing as it was televised, caught up in the White House residence Wednesday evening and tweeted along with a Fox News morning recap Thursday.

The president flatly denied the latest revelations. During Wednesday’s hearing a diplomat testified that another State Department witness overheard Trump asking about Ukraine investigations the day after his phone call with Kyiv.

“First I’ve heard of it,” he said, brushing off the question at the White House.

The Associated Press reported Thursday that a second U.S. Embassy official also overheard Trump’s conversation.

While Trump applauded the aggression of some of his GOP defenders, he felt that many of the lawmakers could have done more to support him and he pressed that case with congressional allies ahead of the next hearing, according to Republicans who were not authorized to speak publicly about private conversations and were granted anonymity.

On Friday, Americans will hear from Marie Yovanovitch, the career foreign service officer whom Trump recalled as the U.S. ambassador to Ukraine after what one State Department official has called a “campaign of lies” against her by the president’s personal lawyer, Rudy Giuliani.

At its core, the impeachment inquiry concerns Trump’s July phone call with Zelenskiy that first came to attention when an anonymous government whistleblower filed a complaint.