For Democrats and Hillary Clinton supporters fearing the next four years under President-elect Donald Trump, there might be a last-ditch effort to reverse the results of Election Day.

A petition urging the Electoral College to reverse their votes was created Thursday on Change.org, and by 2 p.m. had garnered more than 400,000 signatures. 

Its basis rests in a little-known twist in the Constitution. When voters head to the polls on the second Tuesday of every election year, they're not casting a vote for their preferred candidate, but instead are voting to elect individuals, known as "electors," to the Electoral College.

So, if you voted for Donald Trump, and Trump wins the popular vote in your state, electors selected by the Republican party will cast their votes at a later date in their state capitols. 

That date falls on Dec. 19 this year. 

Clinton won the popular vote by 200,000, but Trump had 290 electoral votes to Clinton's 228. (A minimum 270 is required to be elected president.)

The petition on Change.org calls on electors "to ignore their states' votes and cast their ballots for Secretary Clinton" arguing that because she won the national popular vote, she should be the president-elect.

Little stands in the way of electors voting their conscience and refusing to support the candidate of their party or abstaining from voting. These "faithless electors" could face rare repercussions, including fines and misdemeanors, in 29 states and the District of Columbia, according to FairVote.org

Per the New York Times, these faithless electors have never affected the results of an election, and instances of them changing their votes is rare. In fact, there have only been 156 faithless electors since the Electoral College was founded; 71 of those votes were changed because the candidate died before the college cast their votes.

Signers of the petition have called on members of the Electoral College to vote with the will of the people and protect Americans citizens from the perceived dangers of a Trump presidency.

"This is precisely why the Electoral College exists — to protect this nation from electing dangerous demagogues. This is the time to use this built in safety mechanism to pull the switch and prevent a very dangerous man from holding the office of President of the United States. The Electoral College needs to do what it was built for and protect our nation's people," commented California resident Nicole Chiodo.