The president’s lawyers are set to begin their opening arguments Saturday. It’s the first time the White House will publicly present its full case to acquit the president. While it’s essentially guaranteed that the GOP-controlled Senate will not remove Trump from office, his legal defense presents the best public opportunity to win over the handful of Republican senators who could prolong the trial by joining Democrats in their calls for witnesses and documents.

"The president’s team ... has never presented its case since it did not do so in the House,” said Sen. Susan Collins (R-Maine), a key swing vote. “Unlike the House managers, who partially presented when the motions were being debated, the president’s attorneys chose not to do that. It’s not finished yet ... so it’s difficult to judge."

Senate Majority Whip John Thune (R-S.D.) said he hopes Trump’s team will present a "fact-based" defense that counters the Democrats' case.

“I assume at some point they're going to feature [Alan] Dershowitz and Ken Starr, people like that and talk about impeachment in the broader context of what that threshold is,” he said.

Trump’s lawyer Jay Sekulow told reporters Thursday that the White House will argue the president’s actions do not warrant removal from office by presenting “multiple schools of thought on what is and is not an impeachable offense.” Those presentations, Sekulow said, will demonstrate “the actions alleged and the actions of the president do not reach that level no matter which school of thought you’re on.”

Over the past two days, House Democrats have presented their case that Trump should be removed from office for pressuring Ukraine to investigate his political rivals and withholding millions in aid. Democrats will conclude their opening arguments Friday. The House impeached Trump in December on charges of abuse of power and obstruction of Congress.

The president’s team foreshadowed its arguments in a 110-page brief filed Monday — an argument that combined a political assault on the Democrats leading the House’s impeachment investigation with a detailed attack on the process that Democrats used leading up to their Dec. 18 impeachment. A point-by-point rebuttal of Democrats’ specific case was a more limited aspect of the president’s argument.

Senate Republicans are eager to hear from the White House, but several offered a word of advice: keep it concise. Saturday will mark the fifth day of the Senate impeachment proceedings and senators are already getting tired. The trial, which started in earnest on Tuesday, went well past 1 a.m. on the first day this week and ended around 10 p.m. on the second.