House Speaker Nancy Pelosi (D-Calif.) has announced a formal impeachment inquiry into President Donald Trump, calling his conduct “a violation of the law.”

The speaker had been the biggest obstacle to opening a full impeachment inquiry by a floor vote in the House of Representatives. She had previously argued that a fully empowered impeachment inquiry into Trump would be divisive, distract from Democrats’ agenda and force recently elected freshmen members, many in closely divided districts, to take a vote that could upset swing voters.

But then came news that Trump pressured Ukrainian President Volodymyr Zelensky to open an investigation into 2020 Democratic presidential candidate Joe Biden and the former vice president’s son Hunter Biden while withholding military aid approved for the country. This request for foreign intervention in the 2020 election, and the potential act of bribery, pushed Pelosi over the edge.

She has been led there by her caucus. After the new revelations about the president’s wrongdoing emerged, more and more Democratic lawmakers joined calls for Congress to open a full impeachment inquiry. These newly pro-impeachment lawmakers included 11 freshmen members, including a handful from districts that Trump won in 2016.

“These new allegations are a threat to all we have sworn to protect,” seven freshmen lawmakers wrote in an op-ed for The Washington Post on Tuesday. “We must preserve the checks and balances envisioned by the Founders and restore the trust of the American people in our government.”

As part of the new impeachment inquiry authority, Pelosi demanded that Acting Director of National Intelligence Joseph Maguire hand over the whistleblower complaint and report on Thursday when he appears before the House Intelligence Committee.

“He will have to choose whether to break the law or honor his duty to the Constitution,” Pelosi said.

Calls for impeaching Trump began in earnest after the April 18 release of special counsel Robert Mueller’s report on Russian interference in the 2016 election. While the report did not find any criminal acts in Trump’s and his campaign’s efforts to encourage Russian interference in the election, it did outline multiple efforts made by the president to obstruct the investigation.

Throughout the spring and summer, Pelosi resisted calls for moving to impeach the president, including from House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.), instead insisting the House continue its investigations into his wrongdoing and obstruction. But the president has so far successfully tied up Congress in the courts while engaging in an unprecedented level of noncompliance.

Trump then sought to collude with the Ukrainian government the day after Mueller’s testimony before Congress on July 24 appeared to be a flop.

The ongoing congressional investigations “may take us to a place that is unavoidable in terms of impeachment, but we’re not at that place,” Pelosi said in May. She has now reached that place.

This has been updated throughout.