On Monday, it was revealed that Trump decided to review around $400 million in Ukrainian aid in the days before his call with Zelenskiy. Trump conceded that he had asked the Ukrainian leader to investigate Biden, but said his decision to freeze aid was merely an attempt to pressure European leaders to contribute more to the country’s defense.

Trump often speaks in a freewheeling, stream-of-consciousness style that can leave his comments open to a range of interpretations. In the case of the Ukraine call, that may provide fodder for both sides in the debate over impeachment to claim that the president either crossed a line or was simply misinterpreted.

“He is asking a foreign government to help him in his campaign, that is a betrayal of his oath of office,” Pelosi said Tuesday as she announced her plans to formalize the impeachment inquiry.

Pelosi’s move to put her imprimatur on the impeachment inquiry signals a new determination on behalf of House Democrats who so far have been frustrated in their investigative efforts. It also makes an eventual impeachment vote in the lower chamber more likely.

Party leaders are hopeful the announcement could assist in legal battles to compel document disclosures and testimony from the administration that could at least provide political ammunition heading into an election year. At most, they could expose serious misdeeds that could galvanize support to remove Trump from office.

But the decision also carries significant political risk for Democrats. Pelosi long resisted calls from the left wing of her caucus to pursue impeachment, pointing out that a lack of public support for such an undertaking and the risk that it could backfire, strengthening Trump and motivating his base heading into an election year. And the chances of actually removing him from office with Republicans controlling the Senate remain minimal.

‘Weaponized Politics’
Those risks only increase for Democrats if the congressional investigation into Ukraine -- like the years-long inquiry into possible collusion between the Trump campaign and Russia -- finds bad judgment and behavior by the president, but no proof of explicitly illegal behavior. White House officials were eager to draw comparisons to Democratic posturing surrounding Special Counsel Robert Mueller’s report as it became clear Democrats planned to pursue a formal impeachment inquiry on Tuesday.

White House Press Secretary Stephanie Grisham said Democrats continued to “stomp their feet” and “do nothing but weaponize politics.”

“The misguided Democrat impeachment strategy is meant to appease their rabid, extreme, leftist base, but will only serve to embolden and energize President Trump’s supporters and create a landslide victory for the President,” Trump campaign manager Brad Parscale said in a statement.

Trump himself said Democrats “have been doing this stuff for three and a half years” and the impeachment inquiry was “just a continuation of the witch hunt.”