WASHINGTON (AP) — House Speaker Nancy Pelosi launched the House into a formal impeachment inquiry against President Donald Trump on Tuesday, acquiescing to mounting pressure from fellow Democrats and plunging a deeply divided nation into an election year clash between Congress and the commander in chief.

The probe centers on whether Trump abused his presidential powers and sought help from a foreign government for his reelection, actions Pelosi said would mark a “betrayal of his oath of office.” She declared: “No one is above the law.”

Pelosi had long resisted pursuing impeachment, but her caucus moved swiftly in favor of a probe in recent days following reports that Trump asked Ukraine’s president to investigate Democratic foe Joe Biden and his son. Her decision sets up her party’s most urgent and consequential confrontation with a president who thrives on combat, and it injects deep uncertainty in the 2020 White House race.

Trump, who was meeting with world leaders at the United Nations, called the impending inquiry a “witch hunt” and predicted it would be a “positive for me.”