WASHINGTON -- The Democrat-led impeachment investigation is only a few weeks old, but it's moving fast as lawmakers hear from a series of current and former administration officials about U.S. President Donald Trump's dealings with Ukraine.
From diplomats defying the president to Republicans storming secure rooms, the saga is complicated, with a large cast of characters, protests over process and an increasingly convoluted timeline. A quick primer for making sense of it all:
WHY ARE THE DEMOCRATS PURSUING IMPEACHMENT?
For most of the year, House Speaker Nancy Pelosi pushed back on members of her caucus who wanted to begin impeachment proceedings. But that abruptly changed in September, when a whistleblower revealed that Trump had asked Ukrainian President Volodymyr Zelenskiy on a phone call to pursue investigations of Democratic political rival Joe Biden's family and Ukraine's role in the 2016 election. At the same time, the White House was withholding military aid from the country even though it had been approved by Congress.
Pelosi said the probe would focus on whether Trump abused his presidential powers. She stressed that "no one is above the law."
WHAT'S WRONG WITH TRUMP ASKING FOR THE INVESTIGATIONS?
It's against federal law to solicit anything of value from a person from a foreign country in U.S. elections. Biden is running for the Democratic nomination to challenge Trump in 2020.
Prosecutors in Trump's own Justice Department reviewed the matter early on and determined Trump did not violate campaign-finance law, including a prohibition on accepting campaign contributions or a "thing of value" from foreign governments.
Still, the call poses a political problem for Trump. It shows the president's willingness to engage a foreign government for help digging up dirt on a political rival, something that career government officials say is against all diplomatic norms and could endanger national security. Democrats are investigating to decide whether the conduct warrants impeachment, a process spelled out in the Constitution for "treason, bribery, or other high crimes and misdemeanours."
WHY ARE THE INTERVIEWS SECRET? ARE REPUBLICANS BEING SHUT OUT?
The Constitution doesn't say much about how impeachment works, so the Democratic House majority can decide the rules. Democrats are starting the process with closed-door depositions, comparing the process to a secret grand jury preparing for an indictment. Three committees are leading the interviews, and dozens of Democrats and Republicans have been attending and asking questions.
Under both parties, closed-door interviews have been a routine part of congressional investigations.
Still, Republicans have objected to the process, sayings the hearings should be public. Around two dozen Republicans delayed an interview on Wednesday when they stormed the secure room where the testimony was being held and demanded to enter -- even though many of them were not on the three committees that are conducting the depositions.
Democrats say the two parties have equal access to the closed-door interviews and that public hearings will begin within weeks. They have also promised to eventually release transcripts from the depositions.
WHAT ARE OTHER REPUBLICAN CONCERNS?
Republicans say there should be more due process for the president. They point to previous impeachment proceedings and say that they, too, should be given subpoena power and the ability to call witnesses. They also say the House should have an official vote to begin the inquiry, something Pelosi has so far declined to do.
GOP Sen. Lindsey Graham, a top ally of President Donald Trump, introduced a resolution Thursday condemning the Democratic-controlled House for pursuing a "closed door, illegitimate impeachment inquiry."
Republicans have been less outspoken about the substance of the interviews, with many declining to comment as a series of administration witnesses have told lawmakers behind closed doors that they had concerns about the president's behaviour.
Democrats stress that, if impeachment articles are approved against Trump, the Senate would have to conduct a trial where the president's lawyers would be able to defend him and cross-examine witnesses.
WHO HAS TESITIFED AND WHAT HAVE THEY SAID?
Many of the witnesses have been diplomats who were acting as intermediaries between the White House and the Ukrainian government. Former Ukrainian envoy Kurt Volker testified and released text messages to the committee that detailed conversations between him, Gordon Sondland, the U.S. ambassador to the European Union, and Bill Taylor, the top U.S. diplomat in Ukraine. In the messages, Taylor wrote that he thought it was "crazy" to withhold aid from Ukraine for help with a political campaign.
Sondland and Taylor, both of whom still work for the government, have both testified and detailed their concerns about the influence of Trump's personal lawyer, Rudy Giuliani, on Ukraine. Giuliani was leading the push for the investigations.
Taylor testified that he was told the aid would be withheld until Ukraine conducted the investigations that Trump had requested.
Trump has repeatedly said there was no quid pro quo for the Ukraine investigations he was seeking, though witness testimony has contradicted that claim.
WILL THE INVESTIGATION EVER BECOME PUBLIC? AND WILL IT MOVE BEYOND UKRAINE?
At some point in the coming weeks, the closed-door testimony will transition to public hearings. Democrats are expected to call a select group of witnesses who they believe can best tell the story of Trump's actions.
Democrats leading the probe say they are focused on investigating Trump's actions on Ukraine and do not want the narrative to run in too many directions, for fear it will become too complicated for people to follow.
California Rep. Eric Swalwell, a Democrat on the House Intelligence Committee, said it would be tempting to look at Trump's conduct in office like a "10-story condominium" where there are multiple rooms of matters that Democrats want to investigate.
"And you open the Ukraine door and you see all these rats and you assume that well, there's probably shady dealings in these other rooms," Swalwell said. "We're not going to do that right now ... we're focused on what happened with Ukraine."
WHAT'S THE TIMELINE?
As investigators finish their work, the findings will be sent to the House Judiciary Committee, and Democrats are then expected to write articles of impeachment. They have repeatedly said that the White House's refusal to comply is likely to inform an article on obstruction of justice. Other articles could include abuse of power or violations of the emoluments clause, which bans presidents from receiving gifts or payments from foreign governments.
Next would come a committee vote and a vote in the full House.
House Speaker Nancy Pelosi has steadfastly refused to lay out a timeline, saying only that she wants it done "expeditiously." Privately, Democratic lawmakers have said they are aiming for the end of the year.
If the House approves articles of impeachment, the matter would move to the Republican-led Senate for a trial, with senators as jurors. For now, it seems unlikely that the Senate would vote to convict Trump.
While some GOP senators have questioned Trump's behaviour, none has deemed it impeachment-worthy.
Associated Press writers Lisa Mascaro, Alan Fram and Eric Tucker contributed to this report.
