The groundswell of public pressure on the House of Representatives to impeach President Donald Trump rapidly pivoted to the GOP-controlled Senate Wednesday night, with progressive lawmakers and advocacy groups demanding that Republican Majority Leader Mitch McConnell stop his collusion with the White House and allow a fair trial on the articles approved by the House.

Pointing to McConnell's recent vow to work in "total coordination" with the Trump administration on the impeachment trial, Indivisible co-executive director Ezra Levin said the Kentucky Republican "is publicly threatening to orchestrate a sham trial—a cover-up to protect Trump."

"Americans deserve nothing less than the full truth. They deserve to see a fair trial and they are watching closely to see if Senator McConnell delivers one."

—Karen Hobert Flynn, Common Cause

"But he can't do that on his own—he will need to convince his fellow Republican senators to go along with his plan," Levin said in a statement. "So Indivisibles now turn their focus to convincing Republican senators to prioritize their democracy over their party... [A]ny senator who goes along with McConnell's cover-up will never live this down."

In a press conference after the House voted to approve both articles of impeachment against Trump—without the support of a single Republican—House Speaker Nancy Pelosi (D-Calif.) suggested she will not begin the process of sending the articles to the GOP-controlled Senate until it is guaranteed they will receive a fair hearing, rather than a rapid acquittal of the kind McConnell is reportedly planning.

"We cannot name managers until we see what the process is on the Senate side," Pelosi told reporters, referring to the House "managers" selected to present the case for removal to the Senate. "So far we haven't seen anything that looks fair to us. So hopefully it will be fair. And when we see what that is, we'll send our managers."

I asked Pelosi point blank if she could wait "weeks" to send the articles to the Senate until Dems get what they consider a "fair" trial. I also asked if she would "never" send over the articles. She wouldn't rule out either possibility. The latest twist: pic.twitter.com/ZZZuhb5gnP — Manu Raju (@mkraju) December 19, 2019

Heidi Hess, co-director of progressive advocacy group Credo Action, said the onus is now on Senate Minority Leader Chuck Schumer (D-N.Y.) and his fellow Democratic senators to channel the grassroots energy in support of removing the president to force the GOP-controlled Senate to hold an impartial trial.

"The baton is now passed to Sen. Schumer to hold Mitch McConnell accountable for the rigged impeachment trial he's aiming for in the Senate," Hess said in a statement.

"Hundreds of thousands of Americans took to the streets last night demanding that Trump be impeached and removed from office—Schumer and Senate Democrats need to channel that energy and use their power and their platform to call out McConnell's collusion with the White House, Trump's bribery of Republican senators, and Republicans' repeated willingness to choose party above democracy," said Hess. "Now is not the time for feckless leadership in the name of bipartisanship."

While Pelosi did not say what she believes a fair trial would look like, government watchdog group Common Cause—which has demanded McConnell recuse himself from the Senate trial—suggested a number of guidelines in a statement Wednesday night:

Reach bipartisan agreement before the trial begins on procedures to supplement existing Senate impeachment trial rules, including subpoenaing witnesses and admission of evidence;

Allow to be admitted into the Senate trial record as evidence all House impeachment inquiry materials designated by the House Judiciary Committee as publicly available, including transcripts of depositions, public hearing testimony, and other documents;

Allow full presentation of the House managers' case before any votes on motions to dismiss or other motions that could terminate the Senate impeachment trial;

Senators must return any and all political contributions raised by President Trump for any political committee with which senators are affiliated or demand they recuse themselves from the trial;

Permit public access to the Senate trial to the greatest extent possible, limiting transparency only in furtherance of compelling interests, such as protection of classified information, whistleblower anonymity, and confidentiality of final deliberation of articles of impeachment following closing arguments.

Karen Hobert Flynn, president of Common Cause, said the U.S. public deserves "a fair trial of the impeached and disgraced president in the United States Senate—not a show trial to attempt to excuse the abuses of office which led to President Trump's impeachment."

"Americans deserve nothing less than the full truth," said Hobert Flynn. "They deserve to see a fair trial and they are watching closely to see if Senator McConnell delivers one."