A quick summary of the latest news:
House Republicans are expected to push a vote Monday on a resolution to censure Democratic Rep. Adam Schiff, chairman of the House Intelligence Committee, one of the panels investigating impeachment. Republicans, who are a minority in the House, are taking issue with how Schiff is conducting the investigation.
"The very least we can do is censure him," the House Republican leader, California Rep. Kevin McCarthy, said on Fox News Channel's "Sunday Morning Futures."
MORE WITNESSES ON TAP, BUT WILL THEY APPEAR?
William "Bill" Taylor, the diplomat who expressed unease about the Trump administration's hold on U.S. security assistance for Ukraine, is expected to testify in private Tuesday.
Taylor at one point sent a text reading: "As I said on the phone, I think it's crazy to withhold security assistance for help with a political campaign." The text prompted the U.S. ambassador to the European Union, Gordon Sondland, to reply: "Bill, I believe you are incorrect about President Trump's intentions. The president has been crystal clear no quid pro quo's of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign.
"I suggest," he added, "we stop the back and forth by text."
Among others invited for closed-door testimony this week are Philip Reeker, acting assistant secretary of state for Europe; Michael Duffey of the White House's Office of Management and Budget; Alexander Vindman of the National Security Council; and Laura Cooper, deputy assistant secretary of defense for Russia, Ukraine and Eurasia.
CRACKS IN TRUMP'S SUPPORT?
Trump's support among Republicans in Congress has held during the impeachment inquiry, but there are hints of strain amid broader frustrations about the president's handling of foreign policy.
Rep. Francis Rooney, R-Fla., made waves by saying he was keeping an open mind about impeachment. The next day, he announced he would retire at the end of his term.
For now, no other Republicans seem to be following Rooney's lead, but it bears watching in the days ahead as Trump fights to keep impeachment a purely party-line affair.
Asked Sunday on CNN's "State of the Union" what his message is to GOP colleagues as impeachment proceeds, Rooney said: "Well, we only have one thing in our life, and that's our reputation. Everything else is transitory, including life itself. And so I'm not going to ruin mine over anything, much less politics. And I think it's very bad that the system that we have now, which would probably disappoint our founders, is so oriented toward reelection, raising money. And it creates a bias against action. Everybody is quaking in fear of being criticized by the president or something."
An Associated Press-produced animation covers the basics of the impeachment process in less than two minutes: https://youtu.be/TSuLV—kDzeo
IN CASE YOU MISSED IT: Thursday's news conference by acting White House chief of staff Mick Mulvaney confirmed that the decision to hold up military aid to Ukraine was linked to a demand that Ukraine investigate the Democratic National Committee and the 2016 U.S. presidential campaign. Mulvaney later clarified his remarks, and Trump has stood by him.
Mulvaney, in an interview on "Fox News Sunday," was asked whether he offered or thought to office his resignation to Trump, after the news conference, given the criticism he received from his performance.
"No, absolutely not. ... I'm very happy working there. Did I have the perfect press conference? No. But again, the facts were on our side," he said.
Video of Mulvaney's news conference comments: https://youtu.be/iQFAh—MU69E