WASHINGTON (AP) — President Donald Trump’s impeachment trial enters a pivotal week as his defense team resumes its case and senators face a critical vote on whether to hear witnesses or proceed directly to a vote that is widely expected to end in his acquittal. The articles of impeachment charge Trump with abuse of power and obstruction of Congress.

The Capitol Hill maneuvering will be complemented by high-stakes efforts on both sides of the aisle to claim political advantage from the proceedings as the presidential nominating season kicks off in Iowa on Feb. 3.

STAR TURN IN DEFENSE

After a two-hour opening argument Saturday, Trump’s defense team will lay out its case in depth beginning Monday. White House counsel Pat Cipollone said Trump’s lawyers don’t expect to take the full 24 hours allotted to them, but there will be arguments from some familiar faces.

Harvard law professor emeritus Alan Dershowitz, former independent counsel Ken Starr and former Florida Attorney General Pam Bondi will speak on specific topics.

Dershowitz said Sunday he would argue that the charges against Trump are too minor to warrant the president’s removal from office under the Constitution. “Even if true, they did not allege impeachable offenses,” Dershowitz told “Fox News Sunday.”

QUESTION TIME

Once Trump’s team concludes, senators will have 16 hours to ask questions of both the House impeachment prosecutors and the president’s legal team. Their questions must be in writing.

Chief Justice John Roberts will read the questions aloud. He is expected to alternate between both sides of the aisle. Many senators have been talking copious notes throughout the trial in preparation for the question-and-answer time.

Full Coverage: Trump impeachmentSen. John Barrasso, R-Wyo., told reporters Saturday that Republicans expected to get together on Monday to start formulating a list of questions. “We will meet as a conference and decide what questions we want to pose, what the order may be of those of those questions,” he said.

WILL THEY OR WON’T THEY

Under the Senate rules passed last week, senators will vote whether to consider new witnesses and evidence after the Q&A time is elapsed. Four Republicans would have to break ranks to join Democrats in the GOP-controlled Senate to extend the trial for an undetermined amount of time.

If that happens, expect a bitter fight over which witnesses might be called and which documents might be subpoenaed. Democrats have called for testimony from Trump’s former national security adviser, John Bolton, and his acting chief of staff, Mick Mulvaney. An attempt to call either probably would lead to a showdown with the White House, which claims both men have “absolute immunity” from being called to testify before the Senate, even in an impeachment trial. Still, Bolton has said he would appear if issued a subpoena by the Senate.

While Republicans have hoped for a speedy trial, Trump has called for the testimony of former Vice President Joe Biden, his son Hunter and the intelligence community whistleblower whose summer complaint about Trump’s July telephone call with Ukraine’s leader instigated the impeachment inquiry. Hunter Biden served on the board of a Ukraine gas company while his father was vice president.

But some Republicans, including Sen. Lindsey Graham, R-S.C., have expressed resistance to calling those witnesses.

If the vote fails, the Senate could move swiftly to its vote on whether to remove or acquit Trump, giving the president the result he’s been looking for as soon as the end of the week.

THE POLITICS

The trial is resuming with one week to go until the Iowa caucuses, and is again keeping four Democratic contenders — Sens. Bernie Sanders, Elizabeth Warren, Michael Bennet and Amy Klobuchar — in Washington instead of campaigning at a critical point in the race.

While they are trapped in Washington, Trump will venture outside the capital as he seeks both to exert political retribution on Democrats who impeached him and reward a party-switching lawmaker who backed him in the House.

Trump will hold a rally Tuesday in New Jersey to repay the favor to Rep. Jeff Van Drew, who became a Republican last month after voting against the articles of impeachment as a Democrat. And Trump is set to appear in Iowa on Thursday, days before the caucuses.

Meanwhile, Trump is already looking ahead to his likely acquittal, whenever it may come, promising that Democrats will face consequences for trying to remove him from office. “Shifty Adam Schiff is a CORRUPT POLITICIAN, and probably a very sick man,” Trump tweeted Sunday. “He has not paid the price, yet, for what he has done to our Country!”

Schiff, D-Calif., is chairman of the House Intelligence Committee and the lead impeachment manager. Asked on NBC’s ``Meet the Press″ whether he viewed the tweet as a threat, Schiff replied, “I think it’s intended to be.″