WASHINGTON, D.C., USA — The impeachment trial of President Donald Trump is officially underway on Capitol Hill.

However, Mainers protesting in our nation's capital and Maine's Independent Sen. Angus King question whether the trial will be 'fair.'

"Unfortunately, as of [Tuesday] morning, I don't think I can convince anyone this will be a fair trial." Senator King said in his D.C. office.

RELATED: Maine on Impeachment: Senators Collins, King face Pres. Trump's trial

He added the rules Senate Majority Leader Mitch McConnell proposed to Senators two weeks ago, which were intended to mirror the trial for President Clinton in 1999, did not translate in what was released over the weekend.

He specifically pointed to his frustration over the fact the Trump White House refused to release documents and information pertaining to the case, unlike the Clinton White House did. 

King also said the ongoing debate over whether or not to allow witnesses and evidence in the trial should not be so political.

"The position I'm taking isn't partisan, I just want the facts," King said. "I'm supposed to be the jury here and what the jury does is listen to evidence."

On top of not knowing whether or not witnesses and certain evidence will be allowed, King said he fears the proposed rules would stretch arguments late into the evening while mixing in a number of extra steps to the process.

"The whole thing looks like it was designed to hide the proceedings from the American people," King said. "And the American people, however you feel about the outcome, should want to know the facts."

A handful of Mainers were also in our nation's capital Tuesday, demanding a 'fair and impartial trial.' Their main target: republican Sen. Susan Collins.

The republican senator has said repeatedly she is open to the idea of witnesses during the trial, but she is waiting to make her final decision until after hearing opening arguments.

RELATED: Sen. Collins among group of Republicans who fought to extend opening statements in impeachment trial

"I'm not optimistic that this is going to be a fair trial," Mainer, Kate Josephs said.

However, Sen. Collins released a statement Tuesday afternoon explaining her part in pushing Republicans to compromise on trial rules that passed Tuesday, including giving more time for those opening arguments from both sides.

As senators turn to the real arguments of the trial itself, King believes this whole process will be a test of our political system.

"Not only is this a trial in the Senate…It’s a trial of the Senate," King said.