Democratic members of Congress are angrily responding to the release of bombshell emails by Donald Trump Jr. on Twitter, saying that the actions revealed in the emails are not only likely illegal but potentially treasonous. Others also repeatedly emphasized the role of special prosecutor Robert Mueller in continuing to investigate the potential crimes and ultimately letting him pass judgment.

As Vox’s Andrew Prokop explains, the newly released Trump Jr. emails change everything:

The email thread makes clear that Donald Trump Jr. was aware of and willing to support a Russian government effort to help his father’s campaign. It suggests that Kushner and Manafort were also in the loop. And it raises serious questions of how Donald Trump himself could have kept professing to disbelieve claims that Russia was helping him.

Oregon Sen. Ron Wyden, who sits on the bipartisan Senate Intelligence Committee, which has been looking into Trump-Russia ties as well as the firing of former FBI Director James Comey, released a statement saying: “These emails show there is no longer a question of whether this campaign sought to collude with a hostile foreign power to subvert America’s democracy.”

Wyden says DJT Jr email proves collusion pic.twitter.com/0qOxfSumTh — Tom LoBianco (@tomlobianco) July 11, 2017

Minnesota Rep. Keith Ellison, the deputy chair of the Democratic Party, tweeted that Trump Jr.’s revelation was “stunning hypocrisy,” and included a tweet from MSNBC producer Kyle Griffin that showed Trump Jr. during the Republican National Convention calling claims that the Russians were helping his father “disgusting.”

Illinois Sen. Dick Durbin took to Twitter to suggest that Trump Jr. had violated federal law, which prohibits “a person to solicit, accept, or receive a contribution or donation ... from a foreign national.” The relevant part is “contribution,” which Durbin quotes as including anything “for the purposes of influencing any election for Federal office.”

“Contribution” includes “anything of value made by any person for the purpose of influencing any election for Federal office.” — Senator Dick Durbin (@SenatorDurbin) July 11, 2017

Vermont Sen. Patrick Leahy placed the emphasis on the continued Mueller investigation and said that “we must learn exactly what happened” despite the “shifting denials, changed stories, and cascading lies.”

A foreign adversary manipulated our elections and undermined our democracy. We must learn exactly what happened so it never happens again. — Sen. Patrick Leahy (@SenatorLeahy) July 11, 2017

Sp. Counsel Mueller & Congress MUST sort thru the shifting denials, changed stories & cascading lies about Trump team’s contacts w Russia — Sen. Patrick Leahy (@SenatorLeahy) July 11, 2017

Like some others, Illinois Rep. Jan Schakowsky left it to special prosecutor Mueller to decide if the actions of Donald Trump Jr. (as well as those of Jared Kushner and Paul Manafort) were illegal.

Whether Mr. Trump’s decision was criminal or even treasonous will be up to the Special Prosecutor to decide. — Jan Schakowsky (@janschakowsky) July 11, 2017

California Rep. Jackie Speier called the emails “damning” and suggested that they “unravel” the story being pushed by the White House and its allies.

Effort was “…part of Russia and its government’s support for Mr. Trump” – what other parts don’t we yet know about? — Jackie Speier (@RepSpeier) July 11, 2017

Former vice presidential candidate and Virginia Sen. Tim Kaine said in an interview with MSNBC that the emails will provide “wheelbarrows full of new evidence” for Mueller’s probe into the possibility of collusion with the Russians, according to the Hill.

Kaine: Trump Jr. emails provide "wheelbarrows full of new evidence" for Russia probe https://t.co/ji8NH7Cskg pic.twitter.com/JBywcM5EGw — The Hill (@thehill) July 11, 2017

Tennessee Rep. Steve Cohen also called the emails “damning,” saying that it shows “intent, if not actual collusion.” Cohen also added a reference to Nixon’s Saturday Night Massacre, suggesting that Trump might remove the special prosecutor if his investigation gets too close.

Maryland Rep. Elijah Cummings, the ranking Democratic member of the House Committee on Oversight and Government Reform, posted a statement on Medium saying it is a “sad day for our country” and that “the soul of our very democracy depends” on investigating the potential Russia collusion and acting on it.

Hawaii Sen. Brian Schatz asked if any Republican had given any “brave” statements today in response to the emails before suggesting that such statements were unlikely to come.

Has any elected Republican said anything brave today? Oh, never mind. — Brian Schatz (@brianschatz) July 11, 2017

Pennsylvania Rep. Brendan Boyle called the emails “potentially treasonous” and noted that others have gone to jail for lesser crimes.

Besides potentially treasonous there is simply no doubt this is a serious campaign finance law violation. People have gone to jail for less. https://t.co/H1I09L7TuG — US Rep Brendan Boyle (@RepBrendanBoyle) July 11, 2017

New York Rep. Gregory Meeks shared a graphic highlighting the most concerning part of the emails: Donald Trump Jr. saying “I love it” in response to the revelation that the Russian government was supporting his father’s campaign.