House Democrats and defense lawyers face their final day of questioning Thursday in President Donald Trump's impeachment trial, before the Senate holds a crucial vote on whether to consider new witnesses and documents.
Beginning at 1 p.m. ET, senators will have approximately eight hours to submit questions in writing to Chief Justice John Roberts, who is presiding over the trial. Roberts will read each question out loud, alternating between parties.
While Thursday's questions still have the potential to elicit new information, outside the Senate chamber all eyes will be on the Republican whip count.
Senate Majority Leader Mitch McConnell of Kentucky has been working all week to lock down enough votes within his 53-member caucus to block a Democratic attempt to admit additional evidence in the trial.
As of Thursday morning, McConnell's efforts appeared to be paying off. By most counts, Democrats did not yet have enough breakaway Republican votes to compel the chamber to allow new witnesses.
If Friday's expected vote on new witnesses fails, the Senate could move forward with a final vote on whether to convict or acquit the president as early as Friday afternoon. The State of the Union speech is scheduled for Tuesday.
Asked on Thursday morning about his plans for Friday's votes, McConnell played coy. "We'll see what tomorrow brings," he told reporters in the Capitol.
On Wednesday, House impeachment managers and Trump's legal team fielded a range of pointed queries from senators.
House impeachment managers led by Rep. Adam Schiff, D-Calif., were asked to expound on why additional witnesses and documents would be central in Trump's impeachment trial.
On the other side, the defense, led by Trump's personal lawyer Jay Sekulow, was primarily asked about the standards of impeachment and the possible consequences associated with it. They were also pressed on the question of corrupt motives.
While it remains unlikely that the Senate will vote to convict and remove Trump from office, several moderate Republicans had voiced support for calling relevant witnesses and pulling in additional documents.
Democratic House managers have made a forceful case for what they see as the need to call Trump's former national security advisor John Bolton to testify. According to his forthcoming memoir, Bolton personally heard Trump say he wanted to withhold military aid to Ukraine unless the country helped him with investigations into Trump's political rivals, notably former Vice President Joe Biden and his son Hunter.
Trump was impeached by the House last month on charges that included abuse of power stemming from his decision to suspend congressionally mandated foreign aid to Ukraine last summer while he sought investigations from Ukraine's newly elected president. He was also charged with obstruction of Congress, a charge predicated on the White House effort to stonewall a congressional probe of Trump's Ukraine policy.
Thursday's trial session was expected to last well into the evening.