House Democrats announced two articles of impeachment against President Donald Trump on Tuesday, declaring he “betrayed the nation” with his actions toward Ukraine as they pushed toward historic proceedings that are certain to help define his presidency and shape the 2020 election.

The specific charges aimed at removing the 45th president of the U.S.: Abuse of power and obstruction of Congress.

Speaker Nancy Pelosi, flanked by the chairmen of impeachment inquiry committees at the U.S. Capitol, said they were upholding their solemn oath to defend the Constitution. Trump responded angrily on Twitter: “WITCH HUNT!”

The first of the two articles accuses Mr. Trump of abuse of power by soliciting election interference from Ukraine and also conditioning U.S. aid to Kyiv and a White House meeting on those probes. Democrats also allege Mr. Trump obstructed Congress by preventing at least nine officials from testifying and by blocking records from across the federal government from being shared with lawmakers.

“We must be clear: no one, not even the president, is above the law,” Judiciary Committee Chairman Jerrold Nadler (D., N.Y.) said Tuesday.

Voting is expected in a matter of days by the Judiciary Committee, which begins deliberations Wednesday, and by Christmas in the full House. The charges, if approved, would then be sent to the Senate, where the Republican majority would be unlikely to convict Trump, but not without a potentially bitter trial just as voters in Iowa and other early presidential primary states begin making their choices.

In the formal articles announced Tuesday, the Democrats said Trump enlisted a foreign power in “corrupting” the U.S. election process and endangered national security by asking Ukraine to investigate his political rivals, including Democrat Joe Biden, while withholding U.S. military aid as leverage. That benefited Russia over the U.S. as America’s ally fought Russian aggression, the Democrats said.

Trump then obstructed Congress by ordering current and former officials to defy House subpoenas for testimony and by blocking access to documents, the charges say.

The second article, obstruction of Congress, says that Trump directed defiance of the House’s ability to conduct its legal oversight like no other president “in the history of the republic.”

Trump insisted in a new tweet that when he asked Ukraine’s president “to do us a favor” with the investigations, “‘us’ is a reference to USA, not me!” Democrats, however, say Trump’s meaning could not have been clearer in seeking political dirt on Biden, his possible opponent in the 2020 election.

Republicans stand with the president even if they don’t fully address his actions. House GOP Leader Kevin McCarthy said, the vote will be on impeachment not “whether a call is perfect.”

While the impeachment is focused on the Ukraine matter, Trump’s actions toward Russia continue underlie the debate. On Tuesday Trump met at the White House with Sergey Lavrov, the Russian foreign minister just back from Paris efforts to revive peace talks with Ukraine.

At the same time, a top adviser to the Ukraine president, Andriy Yermak, disputed key impeachment testimony from U.S. Ambassador Gordon Sondland, telling Time magazine the two did not speak of the investigations Trump wanted during a Warsaw meeting.

The next steps are expected to come swiftly after months of investigation into the Ukraine matter and special counsel Mueller’s two-year Russia probe.

In his report, Mueller said he could not determine that Trump’s campaign conspired or coordinated with Russia in the 2016 election. But he said he could not exonerate Trump of obstructing justice and left it for Congress to determine.