Advancements in the impeachment inquiry into President Donald Trump were made, a week of tension over the Turkey-Syria conflict resulted in a deal and the Democrats faced off yet again on the debate stage.

All of this and more happened in one busy week for U.S. politics. Each news update threatened to eclipse the last, making it tough to keep track of it all.

We rounded up the biggest news of the week:

Updates on the impeachment inquiry

House Democrats heard testimony from more witnesses about their knowledge of Trump's relationship with Ukraine. Gordon Sondland, the ambassador to the European Union, told House lawmakers that he was disappointed he had to consult with Trump's personal lawyer Rudy Giuliani on Ukraine policy.

"Withholding foreign aid in order to pressure a foreign government to take such steps would be wrong. I did not and would not ever participate in such undertakings," Sondland said.

Also this week, former Russia adviser Fiona Hill testified and Energy Secretary Rick Perry resigned right before his subpoena deadline.

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Turkey and the U.S. negotiate a deal to pause Syria invasion

Vice President Mike Pence announced on Thursday that the U.S. and Turkey had come to an agreement for a five-day pause in Turkey's attack in Syria, allowing longtime U.S. allies the Kurds to withdraw from the region.

Also in Turkey news this week, the House passed a resolution opposing Trump's decision to pull out of northern Syria by an overwhelming majority. And, Democratic leaders in Congress dramatically walked out of a meeting with Trump over Turkey.

This all came after Trump had announced early in the week he signed an executive order authorizing sanctions be placed on Turkey. Pence said those would be lifted if Turkey complies with a permanent ceasefire.

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President's chief of staff stuns at press conference

For the first time, the White House acknowledged that Trump's request for Ukraine to investigate potential corruption in U.S. politics was part of the decision to delay military aid funding.

Acting Chief of Staff Mick Mulvaney said at a press conference "We do that all the time with foreign policy" when asked about a quid pro quo.

But Mulvaney later walked back those comments, saying the media had spun them and that there was never a tie between the aid and the request for an investigation.

At the same press briefing, Mulvaney broke the news that the administration chose Trump's Miami-area resort as the site of the next G-7 summit where world leaders convene.

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12 Democrats face off in the 4th presidential debate

Yes, the fourth Democratic primary debate happened this week; so much has happened since that it feels longer ago. The focus of rivals' attacks seemed to shift from former Vice President Joe Biden to Sen. Elizabeth Warren, who has recently climbed in the polls. She was grilled on her Medicare for All and weather her "wealth tax" plans.

Tuesday was also the first time businessman and billionaire Tom Steyer qualified to take the debate stage, and everyone seemed to hone in on his interesting tie selection.

In no surprise, impeachment and Biden's role in Ukraine were first up in questions from moderators, and Biden tried to put the focus on Trump's corruption instead.

And, Rep. Alexandria Ocasio-Cortez is set to endorse Sen. Bernie Sanders at a rally this weekend.

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Congressional legend Elijah Cummings dies

Washington was rocked by the unexpected death early Thursday of Maryland Rep. Elijah Cummings, who was 68 years old.

He served in the House of Representatives since 1996 and took on the role of chairman of the House Oversight and Reform Committee in January.

House Speaker Nancy Pelosi said in a statement that, "In the House, Elijah was our North Star. He was a leader of towering character and integrity, whose stirring voice and steadfast values pushed the Congress and country to rise always to a higher purpose."

"He worked until his last breath because he believed our democracy was the highest and best expression of our collective humanity and that our nation’s diversity was our promise, not our problem. It has been an honor to walk by his side on this incredible journey. I loved him deeply and will miss him dearly," said his widow, Maya Rockeymoore Cummings, who is chairwoman of the Maryland Democratic Party.

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