House managers will focus on obstruction and the need for witnesses and documents.

Credit…Doug Mills/The New York Times

The House managers prosecuting the case against President Trump will wrap up their arguments on Friday with a focus on the second article of impeachment: the accusation that the president obstructed Congress by blocking witnesses and documents in an attempt to cover up his misconduct.

It will be their last opportunity to appeal to a handful of moderate Republican senators on the question of seeking additional witnesses and documents before the president’s lawyers take center stage. Debate on that vital question is expected to happen early next week, after the conclusion of the arguments and a period of questions about the case from senators.

In the meantime, the Senate trial has tested the patience of senators, who have sat restlessly in their seats for more than 16 hours over two long days. Despite being admonished that they must remain silent and at attention “upon pain of imprisonment,” some have doodled, traded notes, whispered with their neighbors, or even nodded off.

Mr. Trump’s legal defense team is scheduled to begin their presentation on Saturday, angering the president, who complained on Twitter on Friday morning that “my lawyers will be forced to start on Saturday, which is called Death Valley in T.V.”

There have been discussions in the Capitol that senators could start the Saturday session earlier than the usual 1 p.m., which could give them the chance to leave earlier, especially if the White House lawyers decide to reserve more of their presentation for Monday.

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