Alright I've been up for 3.5 hours and had my prerequisite 2 cups of coffee so let's go through all the stuff that just happened. I'll start with a summary of the Democratic argument in short and then move on to what I could reasonably ascertain to be the GOP's flailing attempts to discredit Bob Mueller.
During the election, the Russian government undertook a serious and complex plan to tilt the election in favor of one candidate, Donald Trump. They did this by a variety of methods - GRU spies posing as people online, using the Internet Research Agency for troll-farming, hacking the DNC's emails, and giving those hacked emails to Wikileaks to disseminate being the broadest of them.
At various times - something like 125 of them - the Russians reached out to various Trump campaign officials. One of the most salient one of these meetings was the infamous Trump Tower meeting on June 9. In email exchanges, Don Junior said - referring to the promise of hacked stolen emails from the Clinton campaign - "if it's what you say it is, I love it."
Whether or not the Trump campaign coordinated the release of emails - rising to the level of a criminal conspiracy - could not be proven beyond a reasonable doubt. However, it's true that they knew about the hacked emails and welcomed the help from Russia. The President's statements to George Stephanopoulos indicate that he would hypothetically welcome this kind of aid should it be offered again and that he doesn't see anything wrong with it.
After the election, Donald Trump was worried about an investigation by James Comey into Michael Flynn, his NSA. He repeatedly asked Comey to drop the investigation, to "let go of the Flynn thing." When Comey refused, Trump fired him (under spurious circumstances). Now, Trump is within his rights to fire the FBI Director under Article 2 of the Constitution. Where he's NOT within his rights, per Mueller's testimony, is when there's corrupt intent to obstruct an investigation.
After the firing of Comey, Acting Attorney General Rod Rosenstein appointed Robert Mueller to be the Special Counsel investigating Russia's interference as well as any crimes arising therein. Mueller stayed within very narrow bounds and spun off a host of other issues - like Roger Stone's coordination with Wikileaks and Michael Cohen's hush-money payments to two women Trump was alleged to have hand an affair with - to other jurisdictions. However, he was still well within his rights to explore potential obstruction of justice as that was a crime resulting from the Russia investigation.
When Trump learned of the Special Counsel's appointment, he said "This is the end of my Presidency. I'm fucked." On multiple occasions thereafter, Trump leaned on his subordinates to interfere with the investigation. When he learned that he was in fact a potential target of the investigation, his behavior worsened. He asked Jeff Sessions, multiple times directly and via intermediaries, to "unrecuse" himself and take over the investigation. His White House Counsel, Don McGahn, advised him against this course of action, and he ignored him. Multiple Trump appointees/friends/advisors lied to the President and assured him they had committed obstruction of justice on his behalf. At one point McGahn packed up his office and threatened to resign, but ultimately chose not to.
When the New York Times found out about the Trump Tower meeting, Hope Hicks repeatedly advised the President that it looked bad and the best path forward was complete transparency. Rather than complete transparency, Trump told Junior to lie to the press about the Trump Tower meeting and dictated a knowingly false statement (with Hicks' help). While this act doesn't quite rise to the level of criminal obstruction of justice, it does point to his corrupt intent with regard to (everything else he did).
When Michael Cohen and Paul Manafort were under pressure from Mueller's team and the SDNY prosecutors, Trump publicly threatened them, accused them of "flipping," said flipping should be illegal, threatened to out members of their family for other criminal conduct, dangled the ideas of pardons, and in myriad other ways attempted to influence their testimony to prosecutors and protect himself. (Whether you want to argue that this is witness tampering / witness intimidation under a separate USC statute is up to you).
In general, this is the case presented by Democrats based entirely and exclusively on Mueller's report. Russia hacked the US elections in order to help Donald Trump. Senior members of the campaign aided the Russians (via polling data and messaging strategy) or openly welcomed their interference (via the Trump Tower meeting and the 100+ other meetings). When Trump won the election and learned about the Flynn investigation, he fired James Comey. When the Special Counsel was appointed, he said "I'm fucked." He repeatedly attempted to have subordinates fire Mueller, repeatedly attempted to have Sessions "unrecuse" himself, refused to sit for an interview with Mueller, instructed his aides to lie to the media about their actions, ignored the legal advice of Don McGahn, and provided inadequate answers to Mueller's written questions. While the "underlying crime" of conspiracy wasn't proven, it's unnecessary to the crime of "obstruction." That's sort of the whole point. Further, the obstruction of justice statute does not depend on the *success* of the attempt. If I try to bribe a cop, it's obstruction. If the cop accepts the bribe is immaterial. So it's ultimately of no consequence that McGahn et al *refused* to carry out Trump's order.
Now, onto the GOP counterarguments. Much hay was made of the Steele Dossier, which DID NOT START THE MUELLER PROBE. But credit to the Republicans, they also accused Jospeh Mifsud (which is a DEEP cut) of being some kind of Democratic plant. Mifsud is the guy who originally pitched George Papadopolous that he had a hot student PapaD could work with or some such nonsense, and it was PapaD drunkenly bragging to an Aussie diplomat about his outreach from the Russian government that launched the FBI's counterintelligence probe.
The GOP continued by arguing that absent an underlying crime, Trump in fact did everything in his power to successfully conclude the probe that would totally exonerate him which is on its face a laughable idea. But they're leaning hard on the idea that it was just Trump's stress level that caused him to commit multiple crimes. But also since the crimes DIDN'T WORK, they're not crimes. Then we got the whole Deep State / conflicted Dems narrative. At one point a Republican Congressman argued (follow me here) that obstruction of justice mostly discusses shredding of financial documents and that parsing clause 2(c) is wrong. Much was made of the cost to taxpayers, which was -10 million dollars given how much money we seized from Manafort. Interestingly, the GOP were the only party that used the word "impeachment" up until the last Democrat spoke.
One thing I forgot to mention earlier is that Mueller explicitly stated that he felt he couldn't reach a prosecutorial decision - either to charge or a declination - because of the OLC guidance that a sitting President cannot be indicted. He seemed to indicate that Trump could be indicted upon leaving office. He also didn't specifically refer Trump for impeachment but he did say that the report cites "Constitutional processes." When impeachment came up, he said "you've mentioned one of them."
This felt to me like the Democrats teeing up an impeachment inquiry. Whether or not this hearing moves the public opinion on it or not is a bigger question. But Democrats outlined a series of alleged crimes over the course of months. If we didn't have great reporting from various places, if this had happened all at once, it seems clear that an impeachment inquiry would start immediately.
Anyway, we're about to have round 2, so I'll leave you there.