Former U.S. Secretary of State John Kerry called the House's impeachment inquiry into President Donald Trump a "constitutional imperative" on Wednesday, and said that Trump's request that the Ukrainian president "look into" former Vice President Joe Biden was "an abuse of power."

"If you don't hold [Trump] accountable, say goodbye to rule of law," Kerry told WGBH News' Jared Bowen in an exclusive interview. "You watch what the abuses will be over the course of the next year. This is imperative. This is a constitutional imperative."

On Wednesday, the White House released a memo describing Trump's July phone conversation with newly elected Ukrainian President Volodymyr Zelenskiy. The memo was released the day after House Speaker Nancy Pelosi announced the launching of a formal impeachment inquiry against the president, after months of the speaker resisting calls from fellow Democrats to pursue impeachment.

The call is one part of a whistleblower complaint on the president's activities. After being stymied by the administration, lawmakers on the House and Senate intelligence committees will get their first look at the complaint on Wednesday. Congress is also seeking an in-person interview with the whistleblower, who remains anonymous.

Kerry said he understood Pelosi's hesitation to formally pursue impeachment, but applauded the decision.

"I'm for this now because you cannot turn your back on the nature of this — by the way, days after he escapes from [Attorney General William] Barr misinterpreting the Mueller report," he said. "[Trump is] right back at the old game. Come on, people. We've got to get smart."

Kerry also called on House and Senate Republicans to join Democrats in getting behind the impeachment inquiry.

"If the Republicans don't step up and at least hold their fire until they have a full investigation, they are complicit in the process of a cover up," Kerry said. "They are complicit in this constitutional violation, if not shredding. And I worry about that very greatly."

Kerry said that he was certain that Biden did not act with impropriety, and called on the American public to hold the president accountable.

"I think the American people have common sense," Kerry said. "They just have to read this and see — what is the president doing raising Joe Biden's name in the first instances of the first phone call with a new president he's going to congratulate? It's a disgrace."

At a Boston Speakers Series event at Boston Symphony Hall later Wednesday evening, Kerry said that “everybody has a stake in the system working, and right now it’s not. The institutions have to respond." WGBH is a media partner of the Boston Speakers Series.

“Foreign countries being turned into a president’s opposition research team is not normal,” Kerry added.

WGBH News' Arjun Singh contributed to this report.

Material from the Associated Press was used in this report.