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House prosecutors walked to the Senate side of the Capitol and read the charges out loud.
Chief Justice John G. Roberts Jr. is to be sworn in to his largely ceremonial role.
The White House dismissed a report by an independent federal watchdog, as well as potentially damaging new details about President Trump’s pressure campaign on Ukraine.
One of Trump’s top foes, Adam Schiff, read aloud the articles of impeachment against him.
With the six other House Democrats serving as impeachment managers beside him, Representative Adam B. Schiff of California, the chairman of the Intelligence Committee, ceremoniously walked the articles of impeachment from the House chamber to the Senate chamber midday Thursday. It was the second such journey for the group in the past 24 hours, after formally delivering the articles to the Senate on Wednesday evening.
With the full Senate seated before him, Mr. Schiff read aloud the charges of abuse of power and obstruction of Congress against Mr. Trump. The two charges together are just over eight pages long.
“President Trump thus warrants impeachment and trial, removal from office and disqualification to hold and enjoy any office of honor, trust or profit under the United States,” Mr. Schiff said as he concluded.
That Mr. Schiff would assume the spotlight during this historic moment was sure to irk Mr. Trump, who has targeted him for mockery and criticism and accused him of being the one who committed “high crimes and misdemeanors.”
The White House press secretary, Stephanie Grisham, hit back on Twitter and accused Democrats of the same crimes covered by the articles.
Chief Justice John Roberts will be sworn in today to his largely ceremonial role.
Later this afternoon, Chief Justice John G. Roberts Jr. will arrive at the Senate to be sworn in to preside over the trial. His exact duties have yet to be defined, but as each side argues its case and the deep partisanship between the Democrats and Republicans spills out over a trial that is expected to last weeks, Chief Justice Roberts’s reputation for being independent is at stake.
After Chief Justice Roberts takes his oath to “do impartial justice,” he will turn to the 100 senators and ask them to do the same.
Under Senate rules, the chief justice’s decisions in the trial can be overruled by a majority vote of 51 or more senators.
After all the oaths have been taken, the Senate is expected to summon Mr. Trump to address the charges against him. The president is expected to respond in writing.
Later in the day, the Senate is also expected to set deadlines for trial briefs from the president’s lawyers and the House prosecutors. These dates will start to fill in details about how the trial will proceed.
The day began with a federal office declaring that the president broke the law in withholding aid from Ukraine.
An independent federal watchdog, the Government Accountability Office, found that the Trump administration broke the law when it withheld millions of dollars in security assistance to Ukraine. The report, released Thursday, cited a violation of a 1974 law that protects the spending decisions of Congress. The White House budget office rejected the finding.
The White House and Trump allies continued to undercut a flood of new details coming from a Soviet-born businessman involved in the president’s efforts to pressure Ukraine to help him politically. The businessman, Lev Parnas, is an associate of the president’s personal lawyer, Rudolph W. Giuliani.
Mr. Parnas is under federal indictment but out on bail. In a series of interviews with reporters Wednesday, he alleged that his efforts along with Mr. Giuliani to oust the American ambassador to Ukraine were done with the president’s knowledge and consent. Mr. Parnas said Attorney General William P. Barr was also involved in these efforts.
Earlier this week, House Democrats disclosed documents from Mr. Parnas revealing efforts by him and another man to follow the American ambassador to Ukraine at the time, Marie L. Yovanovitch. On Thursday, the Ukrainian police announced an investigation into whether she was under illegal surveillance while she was stationed there.