U.S. President Donald Trump blasted Democratic leaders Wednesday, making a surprise appearance and cutting short an infrastructure meeting with Democratic leaders after House Speaker Nancy Pelosi accused him of engaging in a coverup.

Trump said he is the most transparent president in U.S. history. “I don’t do coverups,” he told media in the Rose Garden.

Pelosi made her remarks about an hour before she and other congressional leaders were scheduled to meet with Trump at the White House to discuss infrastructure development.

“The fact is, in plain sight in the public domain, this president is obstructing justice and he’s engaged in a coverup — and that could be an impeachable offence,” Pelosi said during an event at the Center for American Progress, a liberal Washington policy advocacy group.

Trump’s anger had been building well before he stepped into the cabinet room for a follow-up meeting with Democrats about an infrastructure deal both parties already suspected was on life support.

Long upset by the wave of Democratic investigations into his administration, Trump was incensed by reports Tuesday that some of his closest former aides — including former communications director Hope Hicks — were being subpoenaed to testify, according to three White House officials and Republicans close to the West Wing, who spoke on condition of anonymity.

The president reached a boiling point just a few hours before the meeting when he saw media coverage of Pelosi’s remark.

Instead of discussing infrastructure as planned, Trump gave an unscheduled news conference where he said he wouldn’t work with Democrats because of what he called “phoney” investigations.

Only when the Democrats’ investigations into him end will he co-operate, Trump said.

Watch Trump explain why he won’t work with Democrats on infrastructure:

Trump said he wouldn’t work with Democrats on infrastructure, given coverup accusations 12:01

Democrats who control the House of Representatives are engaged in a high-stakes power struggle with Trump over their ability to investigate him, with the Republican president stonewalling multiple investigations of him by congressional committees.

The probes range from whether Trump obstructed justice during special counsel Robert Mueller’s inquiry into Russian election meddling, to his personal finances and businesses.

Pelosi and Senate Minority Leader Chuck Schumer responded to Trump’s impromptu statement shortly thereafter, with Schumer describing Trump’s justification for cutting the infrastructure meeting short as a “preplanned excuse.”

“To watch what happened in the White House would make your jaw drop,” Schumer said. “We are interested in doing infrastructure. It’s clear the president isn’t; he is looking for every excuse.”

Watch Pelosi and Schumer address Trump’s remarks:

Nancy Pelosi and Chuck Schumer made a statement on Wednesday in Washington 8:16

Pelosi said congressional Democrats went to the White House “in a spirit of bipartisanship to find common ground” on infrastructure. “For some reason, maybe it was lack of confidence on his part . … he just took a pass,” she said.

“In any event, I pray for the president of the United States.”

The rupture bodes ill for any possible co-operation between the president and the Democrats, signaling deepening political gridlock in Washington.

Pelosi and other senior House leaders have been trying for months to contain demands from more junior Democratic lawmakers to kick off impeachment proceedings against Trump.

Those demands mounted on Wednesday after former White House Counsel Don McGahn ignored a subpoena from the House judiciary committee on Tuesday to appear before it and testify.

“For many of us, we think at least an impeachment inquiry would give us more ability to get witnesses to come to Congress. We’re just trying to figure out how to get the truth,” Democratic Rep. Mark Pocan of Wisconsin told MSNBC.