2020 Democrats are ready to follow Sen. Elizabeth Warren's (D-Mass.) lead — or perhaps Special Counsel Robert Mueller's.

Warren became the first presidential candidate to call for President Trump's impeachment about a month ago, with more contenders jumping on the train in the weeks since. But now, with Mueller's Wednesday reminder that indicting Trump was "not an option" under Department of Justice guidelines, it seems they're all inching toward the resistance's side.

After Mueller made his first public comments about his Russia investigation, Warren quickly tweeted to characterize it as "an impeachment referral." Sen. Kamala Harris (D-Calif.) and South Bend, Indiana Mayor Pete Buttigieg used that same term in their own Wednesday statements.

Former HUD Secretary Julián Castro, Rep. Seth Moulton (D-Mass.), and former Rep. Beto O'Rourke (D-Texas) all renewed their pleas for impeachment on Wednesday as well, while Sen. Cory Booker (D-N.J.) made his for the first time. Rep. Eric Swalwell (D-Calif.), though, only called for impeaching Attorney General William Barr — perhaps a sign of his allegiance to House Speaker Nancy Pelosi (D-Calif.).

Sen. Bernie Sanders (I-Vt.) has only gone so far as to say it "may be time" for the House to start an impeachment inquiry into Trump. Former Vice President Joe Biden has said that if Trump blocked further Congressional probes into his behavior, then Congress would have "no alternative" but to impeach him. Both frontrunners remained silent on Wednesday. Kathryn Krawczyk

"The impeachment train is picking up steam," Jimmy Kimmel said on Monday's Kimmel Live, running through the various depositions House impeachment investigators have conducted in President Trump's Ukraine scandal and catching up on the legal woes of Trump's lawyer Rudy Giuliani. "Make no mistake, the president is melting down like a creamsicle in July," Kimmel said. "He's threatening to sue Nancy Pelosi and Adam Schiff — which you can't do, and not only that, who's he going to get to sue them? All his lawyers are either in jail or going there soon."

"With this and the impeachment and Turkey and Syria and all manner of hell breaking loose," Trump is urging followers to vote for Sean Spicer on Dancing With the Stars, Kimmel said. "And that might be his greatest abuse of power yet."

Trump has "shaken Washington to its core by refusing to recognize the power of Congress to impeach him," Trevor Noah said at The Daily Show. "The question is: Why does the president think he can get away with this?" Neal Brennan had an answer: "Trump doesn't think he got elected; Trump thinks he bought America." When Noah protested, Brennan countered: "Dude, he tried to buy Greenland eight weeks ago" His supporting evidence was kind of persuasive.

"In a normal administration, an impeachment inquiry would be enough drama on its own, but the Trump presidency is like a Black Friday sale happening at the Fyre Festival," Noah said: "Pure chaos!"

Trump faced near-universal condemnation for unilaterally pulling U.S. troops back from Kurdish-held areas of Syria, and now "the thing everyone warned Trump would happen is happening," Noah said. "Turkey invading, Kurds fleeing, ISIS escaping? Like, the Middle East was already a geopolitical Jenga tower, with everyone trying to figure out the right move. And then Donald Trump comes in, he's like, 'What if we move the whole table?'" And while Trump says he's just bringing U.S. troops home, he's actually just shifting them to Saudi Arabia — for cash, Trump bragged. "He is right, that is a first," Noah said. "I don't think America has ever rented out its military before." Watch below. Peter Weber

After federal investigators arrested Lev Parnas and Igor Fruman last week as they boarded one-way flights to Vienna, their close associate Rudy Giuliani wasn't sure he'd been paid "hundreds of thousands of dollars" by Parnas' fraud-mitigation firm, Fraud Guarantee, as Parnas reportedly attested. On Monday, Giuliani was sure, telling Reuters that Fraud Guarantee paid him half a million dollars for legal and technical consulting work last year.

In their indictment of Parnas and Fruman, federal prosecutors say an unidentified Russian businessman arranged for two payments of $500,000 to be wired from foreign bank accounts to a U.S. account controlled by Fruman in September and October 2018. At least part of that money was allegedly used to try to influence U.S. politicians and candidates on Ukraine policy, in violation of federal law. Giuliani told Reuters he's sure his $500,000 came from "a domestic source," though he did not identify the source or explain how he was "100 percent" certain. "I know beyond any doubt the source of the money is not any questionable source," Giuliani insisted.

The federal prosecutors in Manhattan who indicted Parnas and Fruman are also looking into Giuliani's interactions with the duo and Giuliani's other business in Ukraine. Parnas and Fruman were involved in Giuliani's attempts to pressure Ukraine's government to investigate President Trump's domestic political rival Joe Biden. Giuliani is Trump's personal lawyer and fixer, and his legal troubles could also have serious implications for Trump, CNN's Chris Cuomo explained Monday night.

Giuliani's $500,000 paycheck, for work he said started in August 2018 and was completed by 2019, may not seem exorbitant for such a high-flyer, but one of his main attacks against the Bidens is that fellow lawyer Hunter Biden was apparently paid $50,000 a month by a Ukrainian gas company, ostensibly for similar regulatory compliance work. Peter Weber

In his closing statement Monday night, MSNBC host Chris Hayes offered a few thoughts on "the path of least resistance," where organizations turn a blind eye to bad behavior — the NBA's efforts to appease China, for example, or Republican lawmakers pleading ignorance of President Trump's "bile, bigotry, and rank corruption, and abuse of power." But then Hayes veered out on a limb: "Heck, I feel the tug of it myself as my own news organization is embroiled in a very public controversy over its conduct."

Hayes ran through NBC News' pushback against a new book by Ronan Farrow, Catch and Kill, in which Farrow alleges, among other things, that NBC News tried to kill his bombshell report on Harvey Weinstein not only because of pressure from Weinstein's lawyers but also because of concerns about similar allegations about Matt Lauer, then a big star at NBC News.

Hayes noted that NBC News denies these allegations. He seemed skeptical: "One thing, though, is indisputable. Ronan Farrow walked out of NBC News after working on the Weinstein story and within two months published an incredible article in The New Yorker that not only won a Pulitzer but helped trigger a massive social and cultural reckoning that continues to this day."

"The path of least resistance is always there, beckoning seductively with an entirely plausible cover story — 'You've got bigger fish to fry,' 'This isn't the hill to die on,' 'The story isn't ready,'" Hayes said. "But of course it's the very ease of that path that makes it the enemy of the kind of work we as journalists are supposed to do." Peter Weber

Before he fought to keep his tax returns private, President Trump wanted to release them — to show the world how smart he was for lowering his taxable income, a former adviser told CNN.

Sam Nunberg, who served as Trump's political adviser from 2011 to August 2015, said that over lunch in 2013, Trump said he would be fine with his tax returns being released as part of a presidential bid. Nunberg, who did not see the returns himself, told CNN that Trump "thought he could defend the return. I inferred from the conversation that he believed that it was a lower number and he'd look savvy." Another one of Trump's former senior advisers who joined the pair for lunch corroborated Nunberg's account.

In May 2014, Trump declared on Irish television that he would "absolutely" release his tax returns if he decided to run for office, but Nunberg said that six months later, he talked him out of it. During a meeting, he told Trump that under federal election rules, all he had to do was release a broad financial statement, and could leave the tax returns under wraps. Nunberg told CNN he thought this would protect Trump from opponents who might find something explosive in the tax returns. Trump was fine with this, Nunberg added, because "he wanted to look rich rather than smart."

Trump wouldn't announce he was entering the race for another eight months, and he went on to become the first nominee of a major party not to release their taxes in more than three decades. The president's tax returns are now the focus of several legal challenges, and Trump lost an appeal last week to keep House Democrats from subpoenaing his returns from his longtime accountant. Catherine Garcia

Badlands National Park in South Dakota has expanded its bison range, a move that will "contribute to the health and genetic integrity of the herd and continued health of the prairie," the park said.

The bison now have an additional 22,000 acres of grazing land, for a total of 80,193 acres. The park itself is 244,000 acres, with about 1,200 bison calling it home. On Friday, four bison were moved to the new range, returning to the area for the first time in 150 years.

New fencing and cattle guards were installed in the range, thanks to $743,000 in public and private donations. Due to the expansion, visitors will have "more opportunities for viewing, photographing, and learning about bison in their native habitat on the badlands' iconic and stunning landscape," the park said. Former President Barack Obama named the bison the national mammal in 2016. Catherine Garcia

Moving up from the south, Syrian government troops seized several towns in the northeastern part of the country on Monday, one day after reaching an agreement with the Kurdish-led militia that has held control of the area for several years.

The Kurds and Syria reached the deal after President Trump pulled back U.S. troops from the border, giving Turkey the opportunity to invade Syria and launch an assault on the Kurds. The Kurds and United States worked together to fight the Islamic State in Syria, and the Kurds took control over territory lost by ISIS. After the U.S. retreat, the Kurds turned to the Syrian government for added protection against Turkey. Turkish President Recep Tayyip Erdogan considers the Kurds terrorists.

Syrian government forces were able to take control of multiple towns from the Kurds, including Taqba, which has a hydroelectric dam on the Euphrates. Kurdish fighters spent Monday battling Turkish troops and allied Syrian militias in the border towns of Ras al Ain and Tal Abyad. The recent developments are viewed as victories for Syrian President Bashar al-Assad, who counts Russia and Iran as his allies.

Complicating matters is the fact that the U.S. has about 50 tactical nuclear weapons stored at the Incirlik Air Base in Turkey, 250 miles from the Syrian border. Two U.S. officials told The New York Times that over the weekend, State and Energy Department employees were reviewing plans for getting the weapons out of Turkey. They are "essentially Erdogan's hostages," the Times says, and moving them from Turkey would basically end the alliance between the United States and Turkey. Leaving them is just as problematic, as it puts the weapons and U.S. in a vulnerable position. Read more at The New York Times. Catherine Garcia